right we should impose laws on the nature of which we are the resultant. If we would make a durable work, our first thought should be to learn those laws, in order to submit ourselves to them more exactly. We should regard it as an axiom that, given the human organization, there could be only one correct solution in any special case of utilization of force. The problem is to find that solution; and to reach this there is, in my opinion, no shorter way than to study in each sport those select subjects, or experts, who have succeeded by practice in excelling in some specialty. We should for that study arm ourselves with precise means of investigation, which will explain the essential principles of their movements, and take these principles as the rules of education. Although these rules have not yet been established, it is not because experts have been wanting; but the most trained eye can not perceive the subtle differences between the means which experts employ for reaching perfection of movements.
It has been necessary, in order to make a further advance in this study, to create processes which have unveiled a new world of facts. It has been the constant purpose of M. Marey to seek, besides purely subjective sensations, certain experimental data, and thus forestall eternal discussions on obscure points of physiology, in which the fundamental basis itself of discussion—facts—was wanting. The services which the photochronographic method has rendered to biology are well known; in the present case, again, it is invoked as a means of correcting errors. The photographic methods in use at the physiological station give, in short, the complete solution of the analysis of motions, however rapid and complex they may be.
By comparing photographic representations of different subjects or of the same subject at different stages of movement, we may exactly define the manner in which they proceed, seize the slightest differences that distinguish their motions, and perceive the least modifications that are produced in their turn. If these all relate to the same type in the process of perfectionment, we are authorized, after eliminating individual variations, to take and teach what Nature has revealed to us. We can thus study expert subjects under two points of view, for the qualities which they present are derived partly from their structure and partly from their education. Everybody walks, runs, and jumps; but there are few who have a passable gait unless they are trained to it. In short, we learn to walk, run, and jump, as we learn all the rest. We can not well learn alone; and it is one of the essential objects of physical education to perfect the normal gaits as well as all the movements in general. It is furthermore important to extend the individual's life of relation and to accustom it to various movements which are of indisputable utility for defense and for