actions into automatic ones of the secondary kind, in order to make that process clearer, by having it singly in view. Suppose a person who has a perfectly voluntary command over his fingers, to begin to learn to play upon the harpsichord; the first step is to move his fingers from key to key, with a slow motion, looking at the notes, and exerting an express act of volition in every motion. By degrees the motions cling to one another, and to the impressions of the notes, in the way of association so often mentioned, the acts of volition growing less and less express all the time, till at last they become evanescent and imperceptible. For an expert performer will play from notes, or ideas laid up in the memory, or from the connexion of the several complex parts of the decomplex motions, some or all; and, at the same time, carry on a quite different train of thoughts in his mind, or even hold a conversation with another. Whence we may conclude, that the passage from the sensory, ideal, or motory vibrations which precede, to those motory ones which follow, is as ready and direct, as from the sensory vibrations to the original automatic motions corresponding to them; and consequently, that there is no intervention of the idea, or state of mind, called will. At least, the doctrine of association favours this, and the fact shews, that there is no perceptible intervention, none of which we are conscious.
And thus, from the present proposition, and the nineteenth taken together, we are enabled to account for all the motions of the human body, upon principles which, though they may be fictitious, are, at least, clear and intelligible. The doctrine of vibrations explains all the original automatic motions, that of association the voluntary and secondarily automatic ones. And if the doctrine of association be founded in, and deducible from, that of vibrations, in the manner delivered above, then all the sensations, ideas, and motions, of all animals, will be conducted according to the vibrations of the small medullary particles. Let the reader examine this hypothesis by the facts, and judge for himself. There are innumerable things, which, when properly discussed, will be sufficient tests of it. It will be necessary, in examining the motions, carefully to distinguish the automatic state from the voluntary one, and to remember, that the first is not to be found pure, except in the motions of the new-born infant, or such as are excited by some violent irritation or pain.
Cor. I. The brain, not the spinal marrow, or nerves, is the seat of the soul, as far as it presides over the voluntary motions. For, by Cor. II. of the last proposition, the efficacy of the motory vibratiuncles depends chiefly on that part of them which is excited within the brain.
Cor. II. The hypothesis here proposed is diametrically opposite to that of Stahl, and his followers. They suppose all animal motions to be voluntary in their original state, whereas this hypothesis supposes them all to be automatic at first, i.e. involuntary,
