Nor will this appear extraordinary, if we consider the nature of volition itself. In volition, if the doctrine of necessity be true, the mind is altogether passive. Two ideas present themselves in some way connected with each other; and a perception of preferableness necessarily follows.
An object having certain desirable qualities is perceived to be within my reach; and my hand is necessarily stretched out with an intention to obtain it. If a perception of preference, or desirableness, irresistibly lead to animal motion, why may not the mere perception of pain? All that the adversary of automatism is concerned to maintain is that thought is an essential link in the chain; and that, the moment it is taken away, the links that were before no longer afford the slightest ground to expect motion in the links that were after. - It is possible that, as a numerous class of motions have their constant origin in thought, so there may be no thoughts altogether unattended with motion.
Secondly, thought may be the source of animal motion and at the same time be unattended with consciousness This is undoubtedly a distinction of considerable refine-. meet, depending upon the precise meaning of words;Chapter nd, if any person should choose to express himself differently on the subject, it would be useless obstinately to dispute that difference with him. By the consciousness which accompanies any thought, there seems to be something implied distinct from the thought itself. Consciousness is a sort of supplementary reflection, by which the mind not only has the thought, but adverts to its own situation and observes that it has it.
Consciousness therefore, however nice the distinction, seems to be a second thought.
In order to ascertain whether every thought be attended with consciousness, it may be proper to consider whether the mind can ever have more than one thought at any one time. Now this seems altogether contrary to the very nature of mind. My present thought is that to which my present attention is yielded; but I cannot attend to several things at once. This assertion appears to be of the nature of an intuitive axiom; and experience is perpetually reminding us of its truth. In comparing two objects, we frequently endeavour, as it were, to draw them together in the mind, but we seem obliged to pass successively from the one to the other.
But, though it be intuitively true that we can attend to but one thing, or, in other words, have but one thought, at one time, and though intuitive and self-evident propositions do not, properly speaking, admit of being supported by argument, yet there is a collateral consideration, something in the nature of an argument, that may be adduced in support of this proposition.
It is at present generally admitted, by all accurate reasoners upon the nature of the human mind, that its whole internal history may be traced to one single principle, association. There are but two ways in which a thought can be excited in the mind, first, by external impression, secondly, by the property which one thought existing in the mind is found to have, of introducing a second thought through the means of some link of connection between them. This being premised, let us suppose a given mind to have two ideas at the same time. There can be no reason why either of these ideas should prove ungenerative, or why the two ideas they are best fitted to bring after them should not coexist as well as their predecessors. Let the same process be repeated indefinitely. We have then two trains of thinking exactly contemporary in the same mind. Very curious questions will here arise. Have they any communication? Do they flow separately, or occasionally cross and interrupt each other? Can any reason be given, why one of them should not relate to the doctrine of fluxions, and the other to the drama?Chapter n other words, why the same man should not, at the same time, be both Newton and Shakespeare? Why may not one of these coexisting trains be of a joyful and the other of a sorrowful tenor? There is no absurdity that may not be supported upon the assumption of this principle. In fact we have no other conception of fidelity, as it relates to the human mind, than that of a single idea, supersedable by external impression, or regularly leading on, by means of various connections, to an indefinite train of ideas in uninterrupted succession.
But this principle, though apparently supported both by reason and intuition, is not unattended with difficulties. The first is that which arises from the case of complex ideas. This will best be apprehended if we examine it, as it relates to visible objects. 'Let us suppose that I am at present employed in the act of reading. I appear to take in whole words, and indeed clusters of words, by a single act of the mind. But let it be granted for a moment that I see each letter successively. Yet each letter is made up of parts: the letter D, for example, of a right line and a curve, and each of these lines of the successive addition or fluxion of points. If I consider the line as a whole, yet its extension is one thing, and its terminations another. I could not see the letter, if the black line that describes it, and the white surface that bounds it, were not each of them in the view of my organ. There must therefore, as it should seem, upon the hypothesis above stated, to be an infinite succession of ideas in the mind, before it could apprehend the simplest objects with which we are conversant. But we have no feeling of any such thing, but rather of the precise contrary.
Thousands of human beings go out of the world, without ever apprehending that lines are composed of the addition or fluxion of points. An hypothesis that is in direct opposition to so many apparent facts must have a very uncommon portion of evidence to sustain it, if indeed it can be sustained.'