The course of physical science was preparing the same salutary lesson. Locke's great contemporary and friend, Isaac Newton, was his fellow-worker in this tutorial undertaking; nor should Bacon be forgotten, although there is dispute as to the extent and character of his influence. The combined operation of these great leaders of thought was apparent in the altered views of scientific inquirers as to what is competent in research—what is the proper aim of inquiry. There arose a disposition to abandon the pursuit of mysterious essences and grand pervading unities, and ascertain with precision the facts and the laws of natural phenomena. The study of astronomy was inaugurated in Greenwich Observatory. The experiments of Priestley and of Franklin farther exemplified the eighteenth-century key to the secrets of the universe.
The lesson imparted by Newton and Locke and their successors still remains to be carried out and embodied in the subtler inquiries. The bearing upon what constitutes a Mystery, and what constitutes Explanation, or the accounting for appearances, may be expressed thus:—
In the first place, the Understanding can never pass out of its own experience—its acquired knowledge, whether of body or of mind. What we obtain by our various sensibilities to the world about us, and by our self-consciousness, are the foundation, the ABC of everything that we are capable of knowing. We know colours, and we know sound; we know pleasure and pain, and the various emotions of wonder, fear, love, anger. If there be any being endowed with senses different from ours, with that being we can have no communion. If there be any phenomena that escape our limited sensibilities, they transcend the possibility of our knowledge.
It is necessary, however, to take account of the combining or constructive aptitudes of the mind. We can go a certain length in putting together our alphabet of sensation and experience into many various compounds. We can imagine a paradise or a pandemonium; but only as made up of our own knowledge of things good and evil. The limits of this constructive power are soon reached. We are baffled to enter into the feelings of our own kindred, when they are far removed in character and circumstances from ourselves. The youth at twenty cannot approximate to the feelings of men of middle age. The healthy are unable to comprehend the life of the invalid.
[TIME AND SPACE RELATIVE TO OUR FACULTIES.]
To come to the practical applications. The great leading notions called Time and Space are known to us only under the conditions of our own sensibility. Time is made known by all our actions, all our senses, all our feelings, and by the succession of our thoughts; it is experienced as a continuance and a repetition of movement, sight, sound, fear, or any other state of feeling, or of thinking. One motion or sensation is continued longer than another; or it is more frequently repeated after intermission, giving the numerical estimate of time, as in the beats of the pendulum. In these ways we form estimates of seconds, minutes, hours, days. And our constructive faculty can be brought into play to conceive the larger tracts of duration—a century, or a hundred centuries. Nay, by our arithmetical powers we can put down in cipher, or conceive symbolically (which is the meagrest of all conceptions) millions of millions of centuries; these being after all but compounds of our alphabet of enduring or repeated sensations and thoughts. We can suppose this arithmetical process to operate upon past duration or upon future duration, and there is no limit to the numbers that we can write down. But there is one thing that we cannot do; we cannot fix upon a point when Time or succession began, or upon a point when it will cease. That is an operation not in keeping with our faculties; the very supposition is impracticable. We cannot entertain the notion of a state of things wherein the fact of continuance had no place; the effort belies itself. Time is inseparable from our mental nature; whatever we imagine, we must imagine as enduring. Some philosophers have supposed that we must be endowed by nature with the conception of Time, before we begin to exercise our senses; but the difficulty would be to deprive us of that adjunct without extinguishing our mental nature. Give us sensibility, and you cannot withhold the element of Time. The supposition of Kant and others, that it is implanted in us as an empty form, before we begin to employ our senses upon things, is needless; for as soon as we move, see, hear, think, are pleased or pained, we create time. And our notion of Time in general is exactly what these sensibilities make it, only enlarged by our constructive power already spoken of.
[MATTER AND VOID SUPPLEMENTARY.]
While all our senses and feelings give us time, it is our experience of Motion and Resistance—the energetic or active side of our nature alone—that gives us Space. The simplest feature of Space is the alternation of Resistance and Non-Resistance, of obstructed motion and freedom to move. The hand presses dead upon an obstacle; the obstacle gives way and allows free motion; these two contrasting experiences are the elements of the two contrasting facts—Matter and Space. By none of the five senses, in their pure and proper character as senses, can we obtain these experiences; and hence at an earlier stage of inquiry into the mind, when our knowledge-giving sensibilities were referred to the five senses, there was no adequate account of the notion of Space or Extension. Space includes more than this simple contrast of the resisting and the non-resisting; it includes what we call the Co-existing or Contemporaneous, the great aggregate of the outspread world, as existing at any moment, a somewhat complicated attainment, which I am not now specially concerned with. It sufficiently illustrates the limitation of our knowledge by our sensibilities, from the nature of space, to fasten attention on the double and mutually supplementing experience of Matter and Void; the one resisting movement, and giving the consciousness of resistance, or dead strain, the other permitting movement, and giving the consciousness of the unobstructed sweep of the limbs or members. Whatever else may be in space, this freedom to move, to soar, to expatiate (in contrast to being hemmed in, obstructed, held fast), is an essential part of the conception, and is formed out of our active or moving sensibilities. Now, as far as movement is concerned, we must be in one of two states;—we must be putting forth energy without effecting movement, being met by obstacles called matter; or we must be putting forth energy unresisted and effecting movement, which is what we mean by empty space. There is no third position in the matter of putting forth our active energy. Where resistance ends and freedom begins, there is space; where freedom ends, and obstruction begins, there is matter. We find our sentient life to be made up, as regards movement, of a certain number and range of these two alternations; in other words, free spaces and resisting barriers. And we can, by the constructive power already mentioned, imagine other proportions of the two experiences; we can imagine the scope for movement, the absence of obstruction, to be enlarged more and more, to be counted by thousands and millions of miles; but the only terminus or boundary that we can imagine is resistance, a dead obstacle. We are able to conceive the starry spaces widened and prolonged from galaxy to galaxy through enormous strides of increasing amplitude, but when we try to think an end to this career, we can think only of a dead wall. There is no other end of space within the grasp of our faculties; and that termination is not an end of extension; for we know that solid matter, viewed in other ways than as obstructing movement, has the same property of the extended belonging to the empty void. The inference is, that the limitation of our means of knowledge renders altogether incompetent the imagination of an end to either Time or Space. The greatest efforts of our combining faculty cannot exceed the elements presented to it, and these elements contain nothing that would set forth the situation of space ending, and obstruction not beginning.
[ARE TIME AND SPACE INFINITE?]
Under these circumstances, it is an irrevelant enquiry, to ask, Are Time and Space finite or infinite? Many philosophers have put the question, and even answered it. They say Time has no beginning and no end, and Space has no boundaries; or, as otherwise expressed—Time and Space are Infinite: an answer of such vagueness as to mean anything, from a harmless and proper assertion of the limits of our faculties, up to the verge of extravagance and self-contradiction.
When, in fact, people talk of the Infinite in Time and Space, they can point to one intelligible signification; as to the rest, this word is not a subject for scientific propositions, and the attempt at such can lead only to contradictions. The Infinite is a phrase most various in its purport: it is for the most part an emotional word, expressing human desire and aspiration; a word of poetry, imagination, and preaching, not a word to be discussed under science; no intellectual definition would exhibit its emotional force.
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