1. The external senses in their different degrees, especially sight and touch, give us the knowledge of objects that are extended and figured. The body I grasp with the hand or survey with the eye has limits, outlines, angles, surfaces—that is, it has more or less EXTENSION. The inner sense gives us the knowledge of the changes and successions of our mental life. But, amid all these changes, I am conscious there is a something which endures. What is that permanent something which I apprehend under all the varying mental states? It is that principle of personal identity which I call Imyself. To feel and know that I am the same person under all modifications of my mental activity is to endure. Through the aid of memory, which enables me to recall past mental states, and the immediate consciousness of personal existence, through all these changes I obtain the notion of DURATION. The notions of Extension and Duration are clear to my mind.

2. Besides the notion of extended bodies, I have also the notion of position, distance, direction among extended bodies. They exist in various relations to each other; they are here or there, above or below, near at hand or indefinitely remote. It may be the distance between two particles of dust in the sunbeam, or the walls of the room, or between the earth and the sun, or between the sun and the outermost planet of our system, or between the earth and the remotest star which twinkles at the outposts of the universe. Position, distance, direction are all relations. And to all these relations I prefer, with Sir John Herschel, to give the generic name SPACE.[111] Then I have no confusion of thought, and no difficulty or contradiction in using the language of Cousin, Hamilton, and McCosh, when they speak of "determinate and limited space," "particular spaces," "parts of space," and "proportions of space."

Along with the notion of duration (and succession of different states in the same existence), I am conscious that this duration is capable of admeasurement by common standards, and ideally divided into periods of longer or shorter duration. This duration may be measured by successive states of consciousness, or facts of domestic history, or, better still, by the succession of day and night, or the relative position of the sun in the heavens, the revolutions of the moon around the earth, or of the earth around the sun. These are really world-measurements of duration. Since, then, duration can be measured from any point and in any proportions, it is clear that measurement is a purely relative thing—a relation. Of any such thing as "pure time" or "absolute time" we have no knowledge. Time is the measure of finite duration—the correlation of things successive. And if I confine myself to this usage, I am under no necessity of using the paradoxical language of many philosophers, "time is eternity!"

3. We come, lastly, to the notions or ideas of IMMENSITY and ETERNITY, and we ask, Are these necessary ideas of the reason, or can they be confounded with the relations of co-existence and succession on the one hand, or with the attributes of finite extension and duration on the other?

This is not a mere question of systems of philosophy or theology—it is a question of facts. Are the ideas of Absolute Infinity and Eternity necessary intuitions of the reason? The world of sense-perception, the world of science, is phenomenal and contingent. All that is offered to our observation is limited and temporal. The universe surrendered to our science is one of quantities and quantitative relations. It is conditioned by number and form. Its extensions, spaces, and motions are capable of admeasurement. Its worlds and systems are subject to numeration. The phenomena of the universe are all subject to change, they have beginning, succession, and end. But beyond the notions of the limited and the temporal, we find in consciousness the ideas of the illimitable and the eternal; the latter always appearing to reason as the necessary correlates of the former. The finite necessarily supposes the infinite; the temporal necessarily supposes the eternal. The two classes of notions are essentially different, and defy all attempts to generalize them under higher concepts. The infinite is not the totality of finite existences; eternity is not the prolongation of finite durations. Immensity and eternity are absolutely and unconditionally necessary ideas. I can easily conceive the non-existence of any finite thing. I can, without any contradiction, suppose the whole world to be destroyed. All which has a derived and a dependent existence may cease to be. But we can not conceive the source of all existence annihilated. There is one notion which it is impossible for me to annihilate in thought, and that is the notion of absolute being—underived, unconditioned, changeless, eternal being. Despite the destruction of all determinate extension and all finite duration, there remains a Supreme Reality, unlimited, unbeginning, and endless, as an absolute necessity of thought.

Here, then, are two absolute ideas found in the depths of consciousness—the ideas of IMMENSITY and ETERNITY; ideas as real, as natural, and as necessary as the notions of extension and duration. Immensity and Eternity are attributes of God. Extension and Duration are attributes of finite, dependent existence. Space and time are relations between co-existing things and successive events.

If by this somewhat abstruse and, perhaps, too lengthy discussion we have succeeded in proving that Time and Space are simply relations between co-existent things and successive events, which, apart from things and events, have no reality, and are "nothing but the bare possibility of body and change," then we have disentangled the Christian doctrine of absolute creation from the embarrassment occasioned by supposing "the coeval and co-eternal existence of Time and Space as the necessary conditions of the Divine activity." If Time and Space are relations between things and events, then God, as the almighty cause of things and relations, is the efficient cause of space and time, and the creative act was not conditioned by them.

The affirmation of the necessary existence of Space, Time, and Number as co-eternal with and independent of God,[112] prepared the way for and rendered plausible the further affirmation of "the coeval existence of matter as the condition and medium of the Divine agency and manifestation."[113] For if Space, Time, and Number are eternal, why may not Matter be eternal? But why stop with the assertion of the eternity of Space, Time, Number, and Matter? "If we admit that there may be something uncaused, there is no reason to assume a cause of anything." If we admit the eternity of Matter, how can we deny the eternity of Force? We can not conceive of the existence of substance without some properties or qualities, and of all the properties of matter, gravitation or weight seems to approach nearest to an essential, necessary quality. And if we concede the eternity of matter and gravitating force, why not admit the eternity of law—that is, "uniformity of properties and relations;" uniformity in the results arising from the motions and changes of matter? And when so much is granted, why not grant that a consequent Order of the universe must also be eternal? why not grant that the universe is an infinite succession of orderly phenomena without a beginning and end? After the first concession that matter is uncreated and eternal, how can any one refute the doctrine of Hume that the universe never had a beginning, and that under some one or another possible phase—amid the infinite possibility of phases—it is both eternal and infinite? How, after this admission, can we deny that the universe is "a series of events existing eternally in a state of order without a cause other than the eternally inherent laws of matter?"