sweep over its field of vision to and fro, here and there; its movements might conceivably be very numerous, but all the purposes of voluntary acquirement might be served without a very great number.
Because the muscles admit of all these possible stimuli, it does not follow that the brain will ever impart them all. The limits of the motor centers would be the limits of the spontaneous impulses. The workings of the system are brought within a narrow routine, from the deficiency of the nervous matter. There are possibilities of combination of the muscles of the eyes that may never have been realized by the educated eye, far less by the uneducated eye.
Take, again, the swing of the limbs. Many muscles are at work, and many possibilities of union are open; but how few are actually realized! The supposition of the vastness of the possible combinations cuts two ways: it opens up an almost infinite source of active capability. For, although it might be long ere we reached some one particular combination, yet, out of the number of combinations that we might make, we should fall upon manifold obvious utilities that would be soon confirmed into useful habits. The same end may be served by many varieties of means; there might be fifty thousand routes of the hand to the mouth, but, provided it got there anyhow, all would end well. The observation would apply generally to Professor Spence's millions of possibilities: many thousands of them would equally hit the same mark.
5. I might dwell at greater length on the two limiting considerations now adduced; that is to say (1), the limits of the central mechanism, and (2) the equal suitability of many thousands of the supposed possible combinations to given ends. I go on, however, to cite the most important qualification of all—the self-controlling power of the active mechanism. This is the assumption needed to account for the origin of voluntary power, whether in the individual or in the race. To expatiate upon this would only be to repeat what I have said in my writings; and I could not, in a short space, say anything that would be likely to satisfy Professor Spence. I prefer for what remains of my paper to comment upon his own theory, namely, the doctrine of heredity or evolution, which he puts forward as the true solution of the difficulties of the will. In the first place, however, I refer him to "The Emotions and the Will," third edition, p. 318, where I endeavor to show that the postulates of my theory of will—namely, spontaneity, the law connecting pleasure with increased vitality, and the contiguous growth of accidental connections—are indispensable to the evolution doctrine, as stated by Spencer and Darwin. What I mean now to affirm is, that precisely the same difficulty, arising from millions of possibilities of combined action, occurs at every step of our progress by evolution. The only thing that serves to abate the difficulty is that, when a happy combination is once struck, it is hereditarily transmitted and becomes a possession for ever. This would be an important mitigation, if hereditary transmission were easily and soon effected; but the facts show
