That a superficial view of matter, as it presents itself to our mere organs of sense, should lead us to form a different opinion, is, however, what might readily be supposed, because the analogies, which that superficial view presents, are of a kind that seem to mark a loss of identity whenever the state itself is altered.
In experimental philosophy, and in the obvious natural phenomena of the material world, whenever a body changes its state, some addition or separation has previously taken place. Thus, water becomes steam by the addition, and it becomes ice by the loss, of a portion of that matter of heat which is termed by chemists caloric; which loss and addition are, of course, inconsistent with the notion of absolute numerical identity of the corpuscles, in the three states of water as a solid, a liquid, and a gaseous vapour. Perception, by which the mind is metaphorically said to acquire knowledge, and forgetfulness, by which it is metaphorically said to lose knowledge, have, it must be confessed, a very striking analogy to these processes of corpuscular loss and gain; and, since absolute identity seems to be inconsistent with a change of state in the one set of phenomena, with which we are constantly familiar, we find difficulty in persuading ourselves, that it is not inconsistent with a change of state in the other set also. It is a difficulty of the same kind as that which every one must have felt, when he learned, for the first time, the simple physical law, that matter is indifferent as to the states of motion and rest, and that it requires, therefore, as much force to destroy completely the motion of a body, as to give it that motion when at rest. We have not been accustomed to take into account the effects of friction, and of atmospherical resistance, in gradually destroying, without the interference of any visible force, the motion of a ball, which we are conscious of effort in rolling from our hand; and we think, therefore, that rest is the natural state of a body, and that it is the very nature of motion to cease spontaneously. “Dediscet animus sero, quod dedicit diu.” It is a very just saying of a French writer, that “it is not easy to persuade men to put their reason in the place of their eyes; and that when, for example, after a thousand proofs, they are reasonable enough to do their best to believe, that the planets are so many opaque, solid, habitable orbs, like our earth, they do not believe it in the same manner as they would have done if they had never looked upon them in another light. There still comes back upon their belief something of the first notion which they had, that clings to them with an obstinacy, which it requires a continual effort to shake off.”[49]
It is, then, because some substantial loss or gain does truly take place in the changing phenomena of the bodies immediately around us, to which we are accustomed to pay our principal attention, that we learn to regard a change of state in matter as significant of loss of identity, and to feel, therefore, some hesitation in admitting the mental changes of state to be consistent with absolute sameness of substance. Had our observation of the material phenomena been different, there would have been a corresponding difference in our view of the changes of the phenomena of the mind.
If, for example, instead of previously gaining or losing caloric,—as in the constitution of things of which we have our present experience,—the particles of the water had suddenly assumed the state of vapour on the sounding of a trumpet at a distance, and the state of ice immediately on the rising of the sun,—-in short, if the different changes of state in bodies, by which their physical character for the time seems, in many cases, to be wholly altered, had occurred without any apparent loss or gain of substance, we should then no longer have found the same difficulty in admitting the changes of state in mind as consistent with its identity; and the sentient substance, which previously existed in a different state, might then, on the sounding of a trumpet, have been conceived by us to begin to exist, in the state which constitutes that particular sensation of hearing, or, on the rising of the sun, to exist in that different state which constitutes the sun's change of colour as readily as the material substance, previously existing in the form of water, to begin at the same moment, without any essential or numerical change, and consequently with perfect identity, to exist in the new state of steam, or in the state of a chrystalline mass, as solid as the rock from which it hangs as an icicle, or that glitters with its gemmy covering.
But it may be said, that the very supposition which we now make is an absurd one; that the mere presence of the sun in the firmament, at a distance from the water, cannot be supposed to convert it into ice, unless the water gain or lose something, and consequently cease to have absolute identity; and that the case, therefore, is of no value, as illustrating the compatibility of change of state in our various sensations, with unaltered identity of the sentient mind. To this I might answer, that although the presence of the sun certainly does not operate in the manner supposed,—as the sequences of events are now arranged in the great system of nature,—it is only by experience, and not by intuition or reasoning, we know, that the presence of the sun has not the very effect which the separation of caloric now produces, and that there is nothing absolutely more wonderful in the one case than in the other. If our experience had been the reverse of this,—if the change of place of a few particles of caloric had not, as now, converted the liquid water into that solid congeries of crystals which we call ice,—we should then have found as little difficulty in conceiving that it should not have this effect, as we now find in adapting our belief to the particular series of events which constitute our present experience.
It is not necessary, however, to have recourse to suppositions of this kind; since the system of nature, even according to our present experience of it, furnishes sufficient proof of changes as wonderful in the state of bodies produced obviously at a distance, and, therefore, without any loss or addition which can affect their identity. For sufficient evidence of this, I need appeal only to the agency of the celestial gravitation; that gigantic energy of nature which fills the universe, like the immediate presence of the Deity himself,—to which, in the immensity of its influence, the distances, not from planets to planets merely, but from suns to suns, are like those invisible spaces between the elements of the bodies around us, that seem actual contact to our eyes,—and in comparison with which, the powers, that play their feeble part in the physical changes on the surface of our earth, are as inconsiderable as the atoms, on which they exercise their little dominion, are to the massy orbs which it wields and directs at will,—
“Those bright millions of the heavens,
Of which the least full Godhead had proclaim'd,
And thrown the gazer on his knee.”—“Admire
The tumult untumultuous! All on wing,