Page:Popular Science Monthly Volume 51.djvu/339

Rh carrying on war, a statesman conducting affairs of government, a merchant engaged in business negotiations, alike take the path which, having regard to the whole of the circumstances, offers the least amount of resistance to the attainment of the ends in view.

All inorganic and organic movements are therefore alike in the fact that each is due to a greatest stress, and takes place in the direction of a least resistance. It is true, of course, that a pedestrian does not rebound, like the billiard ball, from the resistances which he encounters in trying to find the easiest path through a forest or over the mountains; yet he consciously seeks the path of least resistance, and does so because he is diverted into it by the greater resistances of all other paths; these greater resistances become part of the greatest stress which determines the form of his movement, just as the reactive stress of the cushions forms part of the greatest stress that determines the path of the billiard ball. Inorganic and organic movements differ from each other simply in the fact that by living animals the path of least resistance is more or less consciously chosen, while in the inorganic world the path of least resistance is not chosen. And this unlikeness arises out of a more fundamental unlikeness still, from the fact that movement in the realm of the organic has end for its concomitant, though not necessarily conscious end, while in the motion of things inanimate end is wholly absent. Organic movements, that is to say, are all directed to some end, while in the realm of the inorganic, movements are simply unintelligent effects, results, or products of differential stress. In the form of organic movement, end plays a most important part, while in inorganic movement it has no part at all. Thus a pedestrian may find a circuitous route through a forest the easiest if his only end be to pass through it as quickly as possible; yet, should botanizing be his object, the form of his movement will be quite different, and may very well be the direction of greatest resistance, so far as physical obstacles to movement are concerned. In the case, moreover, of particular ends, numerous opportunities for the exercise of choice present themselves. The more direct path up a mountain is chosen in preference to the one less direct, yet, when the "easier" path is the more dangerous, the traveler takes the safer and more difficult passage. So the more efficient tool is preferred to the less perfect instrument; and so, out of numberless ways in which the ends of life are to be reached, men instinctively and consciously choose those which, by encountering the least possible resistances, involve the minimum expenditure of effort. In the case of organic movements, economy of energy is possible because of the presence of end, the existence of various ways of reaching it, and the possibility of choosing the one which