Instead, however, of considering these kinds of exercise in this empirical way, I will devote a brief space to an examination of them in a more scientific form.
The pleasure of exercise is due first to a purely physical impression, and secondly to a sense of power in action. The first source of pleasure varies of course with our condition and the state of the surrounding circumstances; the second with the amount and kind of power, and the extent and kind of action. In all forms of active exercise there are three powers simultaneously in action,—the will, the muscles, and the intellect. Each of these predominates in different kinds of exercise. In walking, the will and muscles are so accustomed to work together and perform their task with so little expenditure of force, that the intellect is left comparatively free. The mental pleasure in walking, as such, is in the sense of power over all our moving machinery. But in riding, I have the additional pleasure of governing another will, and my muscles extend to the tips of the animal's ears and to his four hoofs, instead of stopping at my hands and feet. Now in this extension of my volition and my physical frame into another animal, my tyrannical instincts and my desire for heroic strength are at once gratified. When the horse ceases to have a will of his own and his muscles require no special attention on your part, then you may live on horseback as Wesley did, and write
