In answer to such a question, it would speedily appear that there were two general causes determining direction of change or growth in the individual, which might be conveniently distinguished from each other--an external and an internal. In the first place the supposed person might say, "External conditions forced me along these lines. My father was a town artisan, but he apprenticed me to a farmer. I grew up a farmer's boy, and became an agricultural type as you see. I did not particularly care for farming, sometimes indeed I would have been glad to be out of it; but practically I succumbed to circumstances, and here I am." But in the second place he might answer thus:--"My father was himself a farmer; I was early used to the craft, and should no doubt have grown up in it, had I not hated it like poison. I loved music, broke away from home, joined a band, got on the musical staff of a small theatre, and am now a professional musician. My frame is comparatively slight, and my hands are of the nervous type, as you see. Of course, I have some of the old agricultural stock left in me, but I feel that that is dying out." The one cause would be a change of external conditions, forcing the man to accommodate himself to them; the other would be a change of internal conditions, an inward growth, expressing itself first in the form of an intense desire, and compelling the man to change himself and probably also his environment in obedience to it. Two such general sets of causes, I say, could be roughly distinguished from each other; and probably indeed are recognised less or more distinctly by everyone as acting to modify his life. Nor can the life of a man at any time be said to be ruled by one of these forces alone. No man is modified by external conditions alone, without any play or reaction of inner needs and desires and growth from within; nor is any man transformed in obedience to an inner expansion without sundry lets and hindrances from without. The two forces are in constant play upon one another; but in some ways that would appear to be the more important which proceeds from the Man (or creature) himself, since this is obviously vital and organic to him, and therefore the most consistent and reliable factor in his modification, while the external force--arising from various and remote causes--must rather be regarded as discontinuous and accidental. I propose, therefore, in these few pages to consider especially this inner force producing modification in man and animals--to try and find out of what nature it is, what is the law, and what are the limits of its action--premising always, as already suggested, that this distinction between "inner" and "outer," which is convenient and easy to handle on certain planes of thought, may ultimately, and in the last resort, prove very difficult or even impossible to maintain.