DURATION.
II
All change implies succession. Hence the duration of contingent beings, inasmuch as they are subject to actual change, involves succession. The duration of the changes brought about by purely spiritual operations transcends our experience; for we are not pure spirits. Hence we have no means of measuring such changes by their intrinsic measure. But the duration of the changes which occur in the material world through local movements lies within the range of our apprehensive faculty, and can be measured by us; for we find in nature many movements which, by their constant recurrence and their uniformity, are calculated to serve as terms of comparison for measuring the length of successive duration.
Definitions of time.—The duration of local movement, which we measure by a given standard, is called “time.” And therefore time may be properly and adequately defined as the duration of local movement: Duratio motus. From this definition it immediately follows that where there is no movement there can be no time. Accordingly, there was no time before creation, as there was no movement. It follows also that the duration of created things, inasmuch as it expresses the permanence of those things in their own being, is not time; for it is of the essence of time to be successive, and there is no succession where there is no change, and no change without movement. Hence, when we say that contingent beings exist in time, we do not refer to their essence or substance as such, but to their successive modes of being, by which their duration acquires its accidental successivity. Were the whole world reduced to perfect stillness by impeding or suspending the actions and movements of all creatures, time would at the same instant cease to flow; for time is not the duration of things, but the duration of movement.
Time may be considered either as a relation or as a quantity. In fact, intervals of successive duration are, like distances, real relations; but when we think of the greater or less extent of space which can be measured with a given velocity between two correlated terms of time, these same intervals exhibit themselves under the form of continuous quantities.
Time, as a relation, is defined by S. Thomas and by all the ancients as Ratio prioris et posterioris motus—that is, as the link between the “before” and the “after” of any movement; and, as a quantity, it is defined as Numerus motus—that is, as a number arising from the mensuration of the movement. This movement is always local, as we have already intimated; for we cannot measure successive duration by any other kind of movement. Hence it is that the duration which is predicated of spiritual substances and of their operations differs in kind from our time. For, since such substances are not subjected to local movements, their duration cannot be measured in terms of space and velocity, as our time, but only in terms of intellectual movements, which have nothing common with the periodical revolutions from which we desume the measure of our days, years, and centuries. When we say that angels have existed for centuries, we measure the duration of their existence by a measure which is altogether extrinsic to them; and in the same manner we measure the duration of our own intellectual operations by a measure extrinsic to them—that is, by comparing it with the duration of some movement occurring in our bodies or in the surrounding world.
Since time is the duration of movement, it is plain that when we perceive movement we immediately perceive time; and since movement implies a continuous change, it is plain also that the greater the number of changes we can distinctly perceive in a given succession, the better we realize the flowing of time. It is for this reason that time seems longer in sickness or in a sleepless night than in good health and in a pleasurable occupation; for gladness and amusement distract our minds, and do not allow us to reflect enough on what is going on around us; whilst anything which affects us painfully calls our attention to ourselves and to our sensations, and thus causes us to reflect on a great number of movements to which in other circumstances we would pay no attention at all. It is for this reason, also, that when we are fast asleep we have no perception of the flowing of time. The moment one falls asleep he ceases to perceive the succession of changes, both interior and exterior, from the consideration of which time should be estimated; hence, when he awakes, he instinctively unites the present now with that in which he fell asleep, as if there had been no intermediate time. Thus, in the same manner as there is no time without movement, there is no actual perception of time without the actual perception of movement.
Measure of time.—We have said that time, as a quantity, is measured by movement. The sense of this proposition is that a body moving with uniform velocity describes spaces proportional to the times employed; and therefore, if we assume as a unit of measure the time employed in describing a certain unit of space with a given velocity, the duration of the movement will contain as many units of time as there are units of space measured by that velocity. Thus, if the revolution of the earth around its axis is taken as the unit of movement, and its duration, or the day, as the unit of time, the number of days will increase at the same rate as the number of revolutions. Speaking in general, if the time employed in describing uniformly a space v be taken as a unit of time, and t be the time employed in describing uniformly a space s with the same constant velocity, we have the proportion—
s:v::t:1.
The unit of time is necessarily arbitrary or conventional. For there is no natural unit of measure in continuous quantities whose divisibility has no end, as we have explained in a preceding article.
The space v uniformly described in the unit of time represents the velocity of the movement; and therefore the duration of the movement comprises as many units of time as there are units in the ratio of the space to the constant velocity with which it is measured. In other terms, time is the ratio of the space described to the velocity with which it is described.
We often hear it said that as time is measured by movement, so also movement is measured by time. But this needs explanation. When we say that time is measured by movement, we mean that time is represented by the ratio of the space to the velocity with which it is described, or by the ratio of the material extension to the formal extending of the movement; for the proportion above deduced gives
t = s/v,
where s represents the length of the movement in space (which length is its material constituent) and v represents its intensity (which is its formal constituent). On the other hand, when we say that movement is measured by time, we either mean that the ratio of the space to the velocity is represented by the time employed in the movement, and thus we merely interchange the members of our equation, by which no new conclusion can be reached; or we mean that the length and the velocity of the movement are measured by time. But this cannot be; for our equation gives for the length of the movement
s = vt;
and this shows that time alone cannot measure the length of the space described. On the other hand, the same equation gives for the velocity
v = s/t;
and this shows that time is not the measure of velocity, as the one diminishes when the other increases.
This suffices to show that the phrase “movement is measured by time” must be interpreted in a very limited sense, as simply meaning that between movement and time there is a necessary connection, and that, all other things remaining equal, the length of the movement is proportional to the length of the time employed. Yet this does not mean that the length of the movement depends entirely on the time employed, for the same length may be described in different times; but it means that the time employed depends on the material and formal extent of the movement, as above explained; for, according as we take different velocities, different lengths will be described in equal time, and equal lengths in different times. It is not the time that extends the movement, but it is the movement that by its extension extends its own time.
The true measure of movement is its velocity; for the measure of any given quantity is a unit of the same kind, and velocity is the unit of movement. Time, as measured by us, is a number which arises from the mensuration of the movement by its velocity; and therefore time results from the movement as already measured. This shows again that time is not the measure of the extent of the movement. We have seen, also, that time is not the measure of the intensity of the movement. It follows, therefore, that the quantity of movement is not measured by time.
Time, being the ratio of two quantities mathematically homogeneous, is represented by an abstract number. Yet the same time may be expressed by different numbers, according as we measure it by different units, as days, hours, minutes, etc. These numbers, however, are only virtually discrete, as time cannot be discontinued.
Balmes from the equation
v = s/t
deduces the consequence that “the velocity is essentially a relation; for it cannot be otherwise expressed than by the ratio of the space to the time.”[81] We think that this conclusion is faulty. Space and time are not homogeneous quantities; hence the mathematical ratio of space to time is not an abstract but a concrete number, and therefore it represents an absolute quantity. Space divided by time is a length divided into equal parts; hence the quotient—viz., the velocity—represents the length of the movement made in the unit of time. And since Balmes admits that the length of the movement is a quantity having a determinate value, we do not see how he can escape the consequence that velocity, too, is a quantity of the same kind, and not a mere relation. “In the expression of velocity,” says Balmes, “two terms enter—space and time. Viewing the former in the real order, abstraction made of that of phenomena, we more easily come to regard it as something fixed; and we comprehend it in a given case without any relation. A foot is at all times a foot, and a yard a yard. These are quantities existing in reality, and if we refer them to other quantities it is only to make sure that they are so, not because their reality depends upon the relation. A cubic foot of water is not a cubic foot because the measure so says, but, on the contrary, the measure so says because there is a cubic foot. The measure itself is also an absolute quantity; and in general all extensions are absolute, for otherwise we should be obliged to seek measure of measure, and so on to infinity” (loc. cit.) This passage shows that a length described in space is, according to Balmes, an absolute quantity. And since the mathematical value of velocity represents a length described in space, as we have just proved, it follows that velocity has an absolute value.
But leaving aside all mathematical considerations, we may show that velocity has an absolute value by reference to metaphysical data. What is velocity but the development in extension of the intensity of the momentum impressed on a material point? Now, the intensity of the momentum is an absolute quantity, equal to the quantity of the action by which it is produced. Hence it is evident that, as the action has an absolute value, greater or less, according to circumstances, so also the momentum impressed has an absolute value; and consequently the velocity also, which is nothing else than the momentum itself as developing its intensity into extension, has an absolute value, and is an absolute quantity.
Balmes thought the contrary, for the following reason: “If the denominator, in the expression of velocity, were a quantity of the same kind as space—that is, having determinate values, existing and conceivable by themselves alone—the velocity, although still a relation might also have determinate values, not indeed wholly absolute, but only in the supposition that the two terms s and t, having fixed values, are compared.… But from the difficulties which we have, on the one hand, seen presented to the consideration of time as an absolute thing, and from the fact that, on the other hand, no solid proof can be adduced to show such a property to have any foundation, it follows that we know not how to consider velocity as absolute, even in the sense above explained” (loc. cit.)
This reason proves the contrary of what the author intends to establish. In fact, if the denominator were of the same kind as the numerator, the quotient would be an abstract number, as we know from mathematics; and such a number would exhibit nothing more than the relation of the two homogeneous terms—that is, how many times the one is contained in the other. It is precisely because the denominator is not of the same kind as the numerator that the quotient must be of the same kind as the numerator. And since the numerator represents space, which, according to Balmes, is an absolute quantity, it follows that the quotient—that is, the number by which we express the velocity—exhibits a quantity of the same nature: a conclusion in which all mathematicians agree. When a man walks a mile, with the velocity of one yard per second, he measures the whole mile yard by yard, with his velocity. If the velocity were not a quantity of the same kind with the space measured, how could it measure it?
True it is that velocity, when considered in its metaphysical aspect, is not a length of space, but the intensity of the act by which matter is carried through such a length. Yet, since Balmes argues here from a mathematical equation, we must surmise or presume that he considers velocity as a length measured in space in the unit of time, as mathematicians consider it; for he cannot argue from mathematical expressions with logical consistency, if he puts upon them construction of an unmathematical character. After all, it remains true that the velocity or intensity of the movement is always to be measured by the extension of the movement in the unit of time; and thus it is necessary to admit that velocity exhibits an absolute intensive quantity measured by the extension which it evolves.
We therefore “know how to consider velocity as absolute,” though its mathematical expression is drawn from a relation of space to time. The measure of any quantity is always found by comparing the quantity with some unit of measure; hence all quantity, inasmuch as measured, exhibits itself under a relative form as ratio mensurati ad suam mensuram; and it is only under such a form that it can be expressed in numbers. But this relativity does not constitute the nature of quantity, because it presupposes it, and has the whole reason of its being in the process of mensuration.
We have insisted on this point because the confusion of the absolute value of velocity with its relative mathematical expression would lead us into a labyrinth of difficulties with regard to time. Balmes, having overlooked the distinction between the mathematical expression and the metaphysical character of velocity, comes to the striking consequence that “if the whole machine of the universe, not excluding the operations of our soul, were accelerated or retarded, an impossibility would be realized; for the relation of the terms would have to be changed without undergoing any change. If the velocity be only the relation of space to time, and time only the relation of spaces traversed, it is the same thing to change them all in the same proportion, and not to change them at all. It is to leave every thing as it is” (loc. cit.) The author is quite mistaken. The very equation
t = s/v,
on which he grounds his argument, suffices to show that if the velocity increases, the time employed in measuring the space s diminishes; and if the velocity diminishes, the time increases. This being the case, it is evident that an acceleration of the movements in the whole machine of the universe would be a real acceleration, since the same movements would be performed in less time; and a retardation would be a real retardation, since the same movements would require more time. We are therefore far from realizing an impossibility when we admit that, in the hypothesis of the author, time would vary in the inverse ratio of the velocity of the universal movement.
Division of time.—Philosophers divide time into real and imaginary. We have already explained this division when speaking of flowing duration. The reality of time evidently depends on the reality of movement; hence any time to which no real movement corresponds is imaginary. Thus if you dream that you are running, the time of your running is imaginary, because your running, too, is imaginary. In such a case the real time corresponds to your real movements—say, to your breathing, pulse, etc.—while the dream continues.
Imaginary time is often called also ideal time, but this last epithet is not correct; for, as time is the duration of local movement, it is in the nature of time to be an object of the imagination. And for this reason the duration of the intellectual movements and operations of pure spirits is called time only by analogy, as we have above stated. However, we are wont to think of such a duration as if it were homogeneous with our own time; for we cannot measure it except by reference to the duration of the movements we witness in the material world.
Time is also divided into past, present, and future. The past corresponds to a movement already made, the future to a movement which will be made, and the present to a movement which is actually going on. But some will ask: Is there really any present time? Does not the now, to which the present is confined, exclude all before and all after, and therefore all succession, without which it is impossible to conceive time? We concede that the now, as such—that is, considered in its absolute reality—is not time, just as a point is not a line; for, as the point has no length, so the now has no extension. Yet, as a point in motion describes a line, so also the now, by its flowing from before to after, extends time. Hence, although the now, as such, is not time, its flowing from before to after is time. If, then, we consider the present as the link of the immediate past with the immediate future—that is, if we consider the now not statically, but dynamically—we shall see at once that its actual flowing from before to after implies succession, and constitutes an infinitesimal interval of time.
This may also be shown by reference to the nature of uniform local movement. When a material point describes a line with uniform velocity, its movement being continuous, its duration is continuous; and therefore every flowing instant of its duration is continuous, as no discontinuous parts can ever be reached in the division of continuum. Hence every flowing instant has still the nature of time. This conclusion is mathematically evident from the equation
t = s/v,
for, v being supposed constant, we cannot assume t = 0 unless we also assume s = 0. But this latter assumption would imply rest instead of movement, and therefore it is out of the question. Accordingly, at no instant of the movement can we assume t = 0; or, which is the same, every flowing instant partakes the nature of time.
The same conclusion can be established, even more evidently, by the consideration of accelerated or retarded movements. When a stone is thrown upwards, the velocity of its ascent suffers a continuous diminution till at last it becomes = 0; and at the very instant it becomes = 0 an opposite velocity begins to urge the stone down, and increases continually so long as the stone does not reach the ground or any other obstacle. Now, a continuous increase or decrease of the velocity means that there are not two consecutive moments of time in which the stone moves at exactly the same rate; and hence nothing but an instant corresponds to each successive degree of velocity. But since the duration of the movement is made up of nothing but such instants, it is clear that the succession of such instants constitutes time; and consequently, as time is continuous, those instants, though infinitesimal, are themselves continuous; and thus every flowing instant is really time.
From this it is plain, first, that although the now, as such, is not time, yet its actual flowing is time.
Secondly, it follows that infinitesimals of time, as employed in dynamics, are not mathematical figments, but realities, for time flows only through infinitesimal instants; and therefore to deny the reality of such infinitesimals would be to deny the reality of time.
Thirdly, we gather that the absolute now differs from an actual infinitesimal of time; because the former, as such, is only a term of time, whereas the latter is the flowing of that term from its immediate before to its immediate after. Hence an infinitesimal of time is infinitely less than any designable duration. In fact, its before and its after are so immediately connected with the same absolute now that there is no room for any designable length of duration between them.
Fourthly, whilst the absolute now is no quantity, the infinitesimal of time is a real quantity; for it implies real succession. This quantity, however, is nascent, or in fieri only; for the now, which alone is intercepted between the immediate before and the immediate after, has no formal extension.
Fifthly, the infinitesimal of time corresponds to a movement by which an infinitesimal of space is described. And thus infinitesimals of space, as considered in dynamics, are real quantities. To deny that such infinitesimals are real quantities would be the same, in fact, as to deny the real extension of local movement; for this movement flows and acquires its extension through such infinitesimals only. And the same is true of the infinitesimal actions by which the rate of local movement is continually modified. These latter infinitesimals are evidently real quantities, though infinitely less than any designable quantity. They have an infinitesimal intensity, and they cause an infinitesimal change in the rate of the movement in an infinitesimal of time.
Evolution of time.—The preceding considerations lead us to understand how it is that in any interval of time there is but one absolute now always the same secundum rem, but changing, and therefore manifold secundum rationem. S. Thomas, in his opuscule De Instantibus, c. ii., explains this truth in the following words: “As a point to the line, so is the now to the time. If we imagine a point at rest, we shall not be able to find in it the causality of any line; but if we imagine that point to be in movement, then, although it has no dimensions, and consequently no divisibility in itself, it will nevertheless, from the nature of its movement, mark out a divisible line.… The point, however, does in no way belong to the essence of the line; for one and the same real term, absolutely indivisible, cannot be at the same time in different parts of the same permanent continuum.… Hence the mathematical point which by its movement draws a line is neither the line nor any part of the line; but, remaining one and the same in itself, it acquires different modes of being. These different modes of being, which must be traced to its movement, are really in the line, whilst the point, as such, has no place in it. In the same manner, an instant, which is the measure of a thing movable, and adheres to it permanently, is one and the same as to its absolute reality so long as the substance of the thing remains unimpaired, for the instant is the inseparable measure of its being; but the same instant becomes manifold inasmuch as it is diversified by its modes of being; and it is this its diversity that constitutes the essence of time.”[82]
From this explanation we may infer that, as each point, or primitive element, of matter has its own now, one in its absolute reality, but manifold in its mode of being, there are in nature as many nows describing distinct lines of time as there are material points in movement. Accordingly, there are as many particular times as there are elements moving in space. The proposition that in time there is only unum instans in re is, therefore, to be limited to the particular time of one and the same subject of motion. S. Thomas did not think of this limitation, because he believed, according to the old astronomical theory, that the movement of the primum mobile—that is, of the supreme sphere—was the natural measure of time; and for this reason he thought that, as the first movement was one, time also was one, and constituted the common measure of all simultaneous movements.[83] But the truth is that there must be as many distinct particular times as there are things actually moving. This is a manifest consequence of the doctrine which assimilates a flowing now to a point describing a line. For as every point in movement describes a distinct line in space, so also must the absolute now of every distinct being describe by its flowing a distinct line of time.
The general time, which we regard as one successive duration, is the duration of the movement from the beginning of the world to our day, conceived in the abstract—that is, without reference to the particular beings concerned in the movement. Time, when thus conceived, is a mere abstraction; whereas the particular times of particular movements are concrete in their continuous extension, notwithstanding their being represented by abstract numbers. If we knew of any special body created and put in movement before any other body, we might regard it as primum mobile, and take its movement, if uniform, as the natural measure or standard of general time; but as we know of no such particular body, and as we have reason to believe that the creation of all matter was made in one and the same moment, we are led to admit an exceedingly great multitude of prima mobilia, every one of which was from the beginning of time the subject of duration. It is clear that we cannot reduce their distinct durations to one general duration, except by making abstraction of all particular subjects, and considering movement in the abstract.
Nevertheless, as we inhabit the earth, we usually restrict our consideration of time to those periodical intervals of duration which correspond to the periodical movements we witness in, or from, our planet; and thus we take the duration of the diurnal or of the orbital movement of the earth as our standard for the measure of time. If other planets are inhabited by rational beings, it is obvious that their time will be measured by other standards, as their diurnal and orbital movements differ from those of our earth.
To the doctrine that time is evolved by the flowing of a single instant, S. Thomas adds an important remark to the effect that the now of contingent things should not be confounded with the now of eternity. He proposes to himself the following objection: “To stand and to move are not essential differences, but only different manners of being. But the now of eternity is standing, and the now of time is moving. The one, therefore, seems to differ from the other in nothing but in the manner of being. Hence the now of time would be substantially the same as the now of eternity, which is absurd.”[84]
S. Thomas replies: “This cannot be true, according to our doctrine; for we have seen that eternity and time differ essentially. Moreover, when of two things the one depends on the other as an effect from a cause, the two things essentially differ; but the now of eternity (which does not really differ from eternity itself) is the cause of time and of the now of time; therefore the now of time and the now of eternity are essentially different. Furthermore, the now of time unites the past with the future, which the now of eternity does not do; for in eternity there is no past and no future, because eternity is all together. Nor has the objection any force. That to stand and to move do not constitute an essential difference is true of those things which are liable both to stand and to move; but that which always stands without possibility of moving differs essentially from that which always moves without the possibility of standing. And this is the case with the now of eternity on the one hand, and the now of time on the other.”[85]
Beginning of time.—Here the question arises whether time must have had a beginning. Those who believe that the world could have been created ab æterno will answer that time could have existed without a beginning. But we are convinced that the world could not be created ab æterno; and therefore we maintain that time must have begun.
Our argument is drawn from the contingency of all things created.
The duration of a contingent being cannot be without a beginning; for the contingent being itself must have had a beginning. In fact, as that cannot be annihilated which has never been in existence, so that cannot be educed from nothing which has never been nothing. It is therefore necessary to admit that every creature had a beginning of its existence, and consequently of its duration also; for nothing endures but inasmuch as it exists.
Nor can this argument be evaded by saying that a contingent being may have initium naturæ, without having initium temporis. This distinction, though suggested and employed by S. Thomas, has no foundation, because the beginning of the created nature is the beginning also of its duration; and he who concedes that there must be an initium naturæ cannot consistently deny the initium temporis. In fact, no contingent being can be said to have been created, if there was no instant in which it was created; in other terms, every creature must be traced to the now of its creation. But the now of its creation is the beginning of its duration no less than of its existence. Surely, whatever has a first now has a beginning of duration; but every creature has its first now—viz., the now of its creation; therefore every creature has a beginning of duration. That the now of creation is the first now is self-evident; for the now of creation is that point of duration in which the passage is made from not being to being; and therefore it marks the beginning of the existence of the created being. And since we cannot say that the duration of the created being preceded its existence, we are bound to conclude that the now of its creation is the beginning of its duration as well as of its existence.
Some will object that we assume what is to be proved—viz., the very now of creation. For, if the world had been created ab æterno, no now of creation could be pointed out. To this we answer that the now of creation, whether we can point it out determinately or not, must always be admitted. To suppress it, is to suppress creation. For, if we assume that a thing had no now of creation, we are compelled to deny that such a thing has ever been created. In other terms, if anything has no beginning of duration, it was always in act, it never lacked actual existence, and it never passed from non-existence to actual existence—that is, it is no creature at all; for to be a creature is to have passed from non-existence to actual existence. And thus we must conclude that to create is to make a beginning of time.
The impossibility of a world created ab æterno has also been argued from the impossibility of an infinite ascending series. The force of this proof does not, however, lie in the absurdity of an infinite series—for such an absurdity, as S. Thomas remarks, has never been demonstrated—but it lies in the necessity of granting a beginning to every term of the series itself; for, if every term of the series has a beginning, the whole series must have a beginning. S. Thomas, as we have just stated, teaches that an infinite ascending series is not to be judged impossible, “even if it were a series of efficient causes,” provided it depend on an extrinsic cause: In infinitum procedere in causis agentibus non reputatur impossibile.[86] This doctrine is universally rejected, and was fiercely attacked even in the time of the holy doctor; but he persisted in maintaining it against all, and wrote a special treatise to defend it contra murmurantes. The reason why S. Thomas embraced this doctrine seems to have been that the creation of the world in the beginning of time was an article of faith; and the saint believed that articles of faith are proved only by authority, and not by natural reason. He was therefore obliged to maintain that the beginning of time could not be demonstrated by reason alone. “The newness of the world,” says he, “cannot be demonstrated from the consideration of the world itself, because the principle of demonstration is the quiddity of things. Now, things, when considered as to their quiddity or species, do not involve the hic et nunc; and for this reason the universals are said to be everywhere and in all time. Hence it cannot be demonstrated that man or any other thing did not always exist.”[87]
To this argument we respectfully reply that, when the necessary conditions of a contingent fact are to be demonstrated, the principle of demonstration is not the abstract quiddity, or intelligible essence, of the things, but the contingency of their actual existence. But it is evident that whatever exists contingently has been educed out of nothing. It is therefore necessary to conclude that all contingent things have had a first moment of existence and of duration.
The Angelic Doctor refers also to a similitude by which some philosophers mentioned by S. Augustine undertook to explain the creation ab æterno. If a foot had been ab æterno pressed on the dust, the impression made by it would be ab æterno. In the same manner the world might have been ab æterno: for God, its maker, is eternal.[88] But we humbly reply that the impression of the foot on the dust cannot be ab æterno if it is contingent. For, if it is contingent, it has necessarily a beginning of its existence, and therefore of its duration also, as we have already shown. Whatever is made has a beginning of duration. Hence the fathers of the church, to prove that the divine Word was not made, thought it sufficient to point out the fact that he was ab æterno like his Father.
S. Thomas, after stating his conclusion that the temporal beginning of the world is not demonstrable, but simply credible, remarks as follows: “And this should be kept in mind, lest, by presuming to demonstrate what is matter of faith by insufficient proofs, we be laughed at by the infidels, who may think that on the strength of such proofs we believe our articles of faith.”[89] This advice is good. But we need not tell our readers that what we hold as of faith we hold on divine authority, irrespective of our philosophical reasons.
Perpetuity of time.—That time may go on without end is an evident truth. But will it go on for ever, or will it cease at last? To this question we answer that time will for ever continue. As long as there will be movement there will be time. There will ever be movement; therefore there will ever be time. The major of this syllogism needs no explanation; for time is nothing but the duration of movement. The minor is quite certain. For not only the rational creatures, but the earth itself and other corporeal things, will last for ever, as is the common doctrine of philosophers, who hold that God will never destroy what he has created. These material things will therefore continue to celebrate God’s glory for ever—that is, will continue to exert their motive power and to bring about divers movements; for such is their nature, and such their manner of chanting the praises of their Creator. Moreover, we know by faith that we shall rise from death and live for ever, and that the glorious bodies of the saints will possess, besides other privileges, the gift of agility, which would evidently be of no use if there were to be no local movement and no succession of time. Hence it follows that time will last for ever.
And let no one say that the Sacred Scriptures teach the contrary. For wherever the Sacred Scriptures mention the end of time, they speak, not absolutely and universally, but only with reference to certain particular periods or epochs of time characterized by some special events or manifestation of divine Providence. Thus we read in the Apocalypse that “there will be time no more”—Tempus non erit amplius—and yet we find that after the end of that time there will be a thousand years; which shows that the phrase “there will be time no more” refers to the time of mercy and conversion. Thus also we read in Daniel that “time has its end”—Quoniam habet tempus finem suum—but we see by the context that he speaks there of the Antichristian epoch, which of course must have an end. And the like is to be said of other similar passages.
The most we can admit in regard to the cessation of time is that, owing to the great catastrophe and the wonderful changes which the consummation of the present epoch shall bring about, the diurnal and the annual revolutions, which serve now as measures of time, may be so modified as to give rise to a new order of things, in which time shall be measured by a different standard. This seems to be the opinion of many interpreters of the Sacred Scriptures; though some of them speak as if after the consummation of the present things there were to be time no more, but only eternity. This manner of speaking, however, is no proof against the continuance of time; for the word “eternity,” when applied to the duration of creatures, means nothing else than sempiternity—that is, time without end, according to the scriptural phrase: Annos æternos in mente habui. We learn from S. Thomas that the word “eternity” is used in three different senses: First, we call eternity the measure of the duration of a thing which is always invariably the same, which acquires nothing from the future, and loses nothing from the past. And this is the most proper meaning of the word “eternity.” Secondly, we call eternity the measure of the duration of a thing which has a fixed and perpetual being, which, however, is subject to accidental changes in its operations. Eternity, when thus interpreted, means what we should call ævum properly; for the ævum is the measure of those things whose being lasts for ever, but which admit of succession in their operations, as is the case with pure intelligences. Thirdly, we call eternity the measure of a successive duration, which has before and after without beginning and without end, or simply without end, though it have a beginning; and in this sense the world has been said to be eternal, although it is really temporal. This is the most improper meaning of the word “eternity”; for the true concept of eternity excludes before and after.[90] Thus far S. Thomas.
We may be allowed to remark on this passage that, according to the principles which we have established in our articles on Substantial Generations,[91] not only the pure intelligences, but all primitive and elementary substances are substantially incorruptible, and have a fixed and permanent being. Hence the distinction made by the holy doctor between ævum and endless time ceases to have a foundation, and the whole difference between the endless duration of spiritual and of material changes will be reduced to this: that the movements of spiritual substances are intellectual, whereas those of the material elements are local.
The phrase “before creation.”—We often hear of such expressions as these: “Before creation there was God alone,” “Before creation there was no time,” etc.; and since such expressions seem to involve a contradiction in terms, we think it will not be superfluous to give their rational explanation. Of course, if the words “before creation” be understood absolutely—that is, excluding any creation either made or imagined—those words will be contradictory. For the preposition before is relative, and implies succession; and it is contradictory to suppose succession without anything capable of succession. When no creature existed there could be nothing flowing from before to after, because there was no movement, there being nothing movable.
Nor can it be said that the now of divine eternity gives us a sufficient ground for imagining any before and after without referring to something exterior to God himself. The now of eternity has in itself neither before nor after; and when we say that it is equivalent to all imaginable time, we do not affirm that it implies succession, but only acknowledge that it is the supreme reason of the possibility of succession in created things. Hence, when we use the phrase “Before creation” in an absolute sense, we in fact take away all real before and all real after; and thus the words “Before creation,” taken absolutely, involve a contradiction. They affirm explicitly what they implicitly deny.
The truth is that, when we use the phrase in question, we express what is in our imagination, and not in our intellect. We imagine that before time there was eternity because we cannot picture to ourselves eternity, except by the phantasm of infinite time. It is for this reason that in speaking of eternity we use the terms by which we are accustomed to express the relations of time. The words “Before creation” are therefore to be understood of a time which was possible in connection with some possible anterior creation, but which has never existed. This amounts to saying that the before which we conceive has no existence except in our imagination.
S. Thomas proposes to himself the question whether, when we say that God was before the world, the term “before” is to be interpreted of a priority of nature or of a priority of duration. It might seem, says he, that neither interpretation is admissible. For if God is before the world only by priority of nature, then it follows that, since God is ab æterno, the world too is ab æterno. If, on the contrary, God is before the world by priority of duration, then, since priority and posteriority of duration constitute time, it follows that there was time before the creation of the world; which is impossible.[92]
In answer to this difficulty the holy doctor says that God is before the world by priority of duration, but that the preposition “before” designates here the priority, not of time, but of eternity. Or else we must answer, he adds, that the word “before” designates a priority, not of real, but of imaginary, time, just as the word “above” in the phrase “above the heavens there is nothing” designates an imaginary space which we may conceive by thinking of some imaginary dimensions superadded to the dimensions of the heavens.[93]
It strikes us that the first of these two answers does not really solve the difficulty. For the priority of eternity cannot mean but a priority of nature and of pre-eminence, by which God’s permanent duration infinitely excels, rather than precedes, all duration of creatures. In accordance with this, the objector might still urge on his conclusion that, if God does not precede the world, the world is ab æterno like God himself. The second answer agrees with what we ourselves have hitherto said. But as regards the objection proposed, it leaves the difficulty entire. For, if God was before the world by a priority, not of real, but of imaginary time, that “before” is imaginary, and not real. And the consequence will be that God was not really “before” the world, but we imagine him to have been so.
We must own that with our imperfect language, mostly fashioned by imagination, it is not easy to give a clear and popular solution of the objection. Perhaps the most summary manner of dealing with it would be to deny the inference in the first horn of the dilemma—viz., that if God is before the world by priority of nature only, then the world will be ab æterno as much as God himself. This inference, we say, is to be denied; for it involves the false supposition that a thing is ab æterno if there is no time before it; whereas that only is ab æterno which has no beginning of duration.
Thus there is no need of saying that God precedes the world in duration; for it suffices to admit that he was before the world by priority of nature and of causality. The duration of eternity has no “before” and no “after,” though we depict it to ourselves as extending into indefinite time. Even the verb was should not be predicated of God; for God, strictly speaking, neither was, nor will be, but permanently is. Hence it seems to us that it would be a contradiction to affirm that God was before the world by the duration of his eternity, while we acknowledge that in his eternity there is no “before.” But enough about this question.
The duration of rest.—Supposing that a body, or an element of matter, is perfectly at rest, it may be asked how the duration of this rest can be ascertained and measured. Shall we answer that it is measured by time? But if so, our reader will immediately conclude that time is not merely the duration of movement, as we have defined it, but also the duration of rest. On the other hand, how can we deny that rest is measured by time, when we often speak of the rest of a few minutes or of a few hours?
We might evade the question by answering that nothing in creation lies in absolute rest, but everything is acting and acted upon without interruption, so that its movement is never suspended. But we answer directly that, if there were absolute rest anywhere in the world, the duration of that rest should be measured by the duration of exterior movements. In fact, rest has no before and after in itself, because it is immovable, but only outside of itself. It cannot therefore have an intrinsic measure of its duration, but it must borrow it from the before and after of exterior movement. In other words, the thing which is in perfect rest draws no line of time; it has only a statical now which is a mere term of duration; and if everything in the world were in absolute rest, time would cease altogether. Hence what we call the duration of rest is simply the duration of a movement exterior to the thing which is at rest.
This will be easily understood by considering that between a flowing and a standing now there is the same relation as between a moving and a standing point.
Now, to change the relation of distance between two points in space, it suffices that one of them move while the other stands still. This change of distance is measured by the movement of the first point; and thus the point which is at rest undergoes, without moving, a continuous change in its relation to the moving point. In a similar manner, two nows being given, the one flowing and the other standing, the time extended by the flowing of the first measures the change of its relation to the second, and consequently, also, the change of the relation of the second to the first. This shows that the time by which we measure the duration of rest is nothing but the duration of the movement extrinsic to the thing at rest.
But, as we have said, nothing in creation is in absolute rest; and therefore what we consider as resting has really some movement imperceptible to our senses—as, v.g., molecular vibrations—by which the duration of its supposed rest is intrinsically measured. In God’s eternity alone there is perfect immobility; but its duration cannot be measured by time, even as an extrinsic measure, because the standing duration of eternity has nothing common with the flowing duration of creatures. As local movement cannot measure divine immensity, so flowing duration cannot measure divine eternity; because, as the ubi of a creature never changes its relation to God’s immensity, so the quando of a creature never changes its relation to God’s eternity.
Continuity of time.—We will conclude with a few remarks on the continuity of time. That time is essentially continuous is evident; but the question has been proposed: What if God were to annihilate all existing creatures, and to make a new creation? Would the instant of annihilation be immediately followed by the instant of the new creation, or could there be an interval of time between them?
The right answer to this question is that between the annihilation and the new creation there would be no time: because there cannot be time without succession, and no succession without creatures. Yet, it would not follow that the instant of the annihilation should be immediately united with the instant of the new creation; in other words, the duration of the new world would not be a continuation of the duration of the world annihilated. The reason of this is that there cannot be a continuation of time, unless the same now continues to flow. For when one flowing now ceases to be, and another begins, the line of time drawn by the first comes to an end, and another line, altogether distinct, begins, and this latter cannot be a continuation of the former. If the English mail, for instance, reaches New York at a given instant, and the French mail at the same instant starts from Paris, no one will say that the movement of the French mail is a continuation of the movement of the English mail. Hence the duration of the movement of the one is not the continuation of that of the other.
Moreover, from what we have seen about the distinct lines of time described by distinct subjects of flowing duration, it is plain that even the durations of simultaneous movements are always distinct from one another, as belonging to distinct subjects; and accordingly, when one of the said movements ceases, the continuation of the others cannot be looked upon as its continuation. Hence, if the present world were annihilated, its duration would cease altogether; and the duration of a newly-created world would draw a new line of time quite distinct from that of the present world, though between the end of the one and the beginning of the other there would be no time. “The two worlds in question,” as Balmes remarks, “would have no mutual relation; consequently there would be neither distance nor immediateness between them.”[94]
Time is formally continuous. Formal continuity we call that of which all the constituent elements have their own formal and distinct existence in nature. In time such elements are those flowing instants which unite the immediate past with the immediate future. This continuity is essentially successive. It is owing to its successivity that time, as well as movement, can be, and is, formally continuous. For no formal continuum can be simultaneous, as we have shown where we refuted the hypothesis of continuous matter.[95] But let this suffice about time.