But what of the energy? The greater the expenditure of energy, the more work done, the more tissue destroyed. The more tissue destroyed, the more food needed, and the more ingested. But this does not prove that the extra amount of food has _created_ the extra energy! That would be putting the cart before the horse with a vengeance! And yet this is what is universally done by physiologists in considering these experiments! Perhaps I cannot do better than to quote, just here, a portion of the excellent Introduction which Dr. A. Rabagliati, F.R.C.S., F.F.C.P., etc., wrote to my book, and which really states the case more clearly than I stated it myself. He says in part: "To take an analogy: It seems to me it would be as pertinent to argue that because the strings of a violin or harp waste in proportion to the quantity of music evolved through or by means of them, therefore the waste of the strings is the cause of the music, while in fact it is the hand of the player, and even the spirit behind the hand, which is the real and efficient cause of the music. So the form of the infinite and universal energy, which we may call erg-dynamic, is the cause of the waste of the body through which it works; and this is at once made good by the increased trophic metabolism which occurs, to replace the waste--this increased trophic metabolism showing itself in increased O_2 intake and coincidently or correspondingly with increased CO_2 output. If the strings of a musical instrument were self-repairing, we might perhaps be induced to think that the material which fed the strings was the _cause_ of the music, since in that case some measure of the waste would probably be discoverable in the _debris_ emitted; and we might imagine that the _debris_ was the measure of the music, while what it really was, was the measure of the waste of the strings, when they were made the instrument of the music. If a spade is used in digging, the spade wastes in proportion to every spadeful of earth it is made to lift. The more it digs, the more it wastes. If we could arrange that a stream of fine steel particles flowed into the spade, to replace the waste caused by each act of digging, we might perhaps come to think that these fine steel particles were the cause of the digging, especially as the quantity of them required would always be exactly proportioned to the amount of work done. Nevertheless, this would be a very inconsequent assumption. Yet this is the assumption invariably made by modern scientists."