To our conclusion, that TIME is the equivalent of Pastness, Presentness, and Futureness, combined, it may be objected, that the word Time is applicable to all the three cases; as we can say, past time, present time, and future time, all with equal propriety. This, however, is so far from being any presumption against the conclusion, that it is a clear confirmation of it; since Time, standing by itself, marks no particular case, and, in order to do so, must have another mark applied to it to limit its signification. It is only because Time marks all the cases of pastness, presentness, and futureness, that it needs the marks past, present, or future, to confine its meaning; present time being merely another name for presentness, future time, for futureness, and past time, for pastness. The same thing is seen in the case of all other abstracts. Redness is the name of a certain colour, in all its modifications, and to whatever object belonging. But by the addition of an appropriate mark, we confine its meaning to any particular case; as when we say, the redness of a rose, the redness of scarlet, and so on.
120 The accounts, which have been rendered of Time by different philosophers, so far as they have in them any acknowledged accuracy, are, all of them, parts, and but parts, of the analysis which we have thus been presenting. Dr. Reid says, Memory gives us the conception and belief of finite intervals of duration; and these we enlarge by our mental processes to infinity.[4*] We have already seen what Memory is. It is not a faculty, as Dr. Reid supposes, which “gives” any thing; it is an idea, formed by association of the particulars of a certain train; a train of antecedents and consequents, of which the present feeling is one extremity. Pastness is included under the term Memory. Memory is the name of a certain whole, and Pastness is the name of a part of that whole. Memory is a connotative term; what it notes, is the antecedence and consequence of the several parts of that which forms the chain of the remembrance; what it connotes, are the feelings themselves, the objects remembered. When what it connotes is left out, and what it notes is retained, we have the idea which is expressed by pastness.
[4*] Intellect. Powers. Essay III. ch. v. p. 583.
In the chain of memory, consisting of antecedent, antecedent, antecedent, traced back to any length from the present feeling, we call that which immediately precedes the present, the nearest; the next, we call more distant; the next, more distant still; and that, between which and the present feeling the greatest number of successions intervenes, we call the most distant, also the farthest back; but the farthest back of a series of successions, is the oldest, that between 121 which and the present time the greatest length of time has intervened. Greatest length of time, therefore, in this case, is only another name for greatest number of successions.
It has been already seen, that there is nothing in which we are so deeply interested, as an accurate knowledge of the antecedents and consequents, in the midst of which we exist. Of the different innumerable trains of antecedents and consequents which it is important for us carefully to mark, it is observed, that some succeed more quickly, some less. While the long pendulum of an eight-day clock is performing one oscillation, the short pendulum of a table-clock performs two or three.
What that is, to which we give the name of quickness, or slowness, in those successions; in other words, what is the state of consciousness which we have thus occasion to mark; has already been seen. Every succession, observed by us, is a case of sensation and memory; sensation of the consequent, memory of the antecedent. If we have observed simultaneously the oscillations of the two pendulums, mentioned above, we remember two or three antecedent oscillations of the short pendulum, before we get back to one of the long. It is a mere case, therefore, of the greater or less number of antecedents in a chain of memory, expounded in a preceding chapter.
In the knowledge, so important to us, of antecedents and consequents, it is not enough that we know what antecedents are followed by what consequents; much depends upon the quickness or slowness of the successions. It is, therefore, of the highest importance that we should have the means of marking them.
122 What we do is, to take some well-known case of successions, and to make that a standard, by which to ascertain the rest. We take, for example, the oscillations of a pendulum. So many of these we call a minute. So many minutes we call an hour. These minutes and hours, then, are so many oscillations, that is successions. We call them measures of time. But things are measurable only by parts of themselves; extension by extension, weight by weight, and so on. What is measured by succession, therefore, is itself nothing but succession.
Having assumed a certain case of successions as a standard, and marked it into quantities, by distinctive names, we mark or name all other successions, by the names applied to the standard case. Thus, that grand succession, on which so much of what we are interested in depends, a revolution of the earth upon its own axis, we distinguish, by the term, twenty-four hours; which we also call by the name, day; and afterwards make use of, as a standard, to mark still slower successions, such as a revolution of the moon about the earth, a revolution of the earth about the sun. In all these measurements, and expressions, of time, it is still seen, that there is nothing in reality conceived but successions.
Beside the standards, more distinctly conceived and expressed, there is always, in these estimates of time, a tacit reference to another standard, which is regarded as the unit, or minimum of time. The case here is precisely analogous to that of the unit, or minimum, of extension, which we have already observed. Our tactual, and muscular, senses are not sufficiently fine to discern objects of less than a certain magnitude. 123 The least which they can discern is tacitly assumed as the unit of extension. Nor are any of our senses fine enough to discern successions which have more than a certain degree of rapidity. Thus, if the seven primitive colours are made to pass with a certain velocity before the eye, they do not appear separate, but blended into one continuous white. In like manner, if sounds are made to succeed one another, at first, slowly, afterwards, with greater and greater rapidity, they cannot, at last, be distinguished as different sounds, but appear as one continuous sound. In fact, this is probably the account of all sounds, which are merely effects of the vibrations in the air, and therefore pulses; but often so quick, in succession, that no interval is distinguishable, and the perception is that of a continuous sound.