Many persons imagine that, if they returned to a primitive diet of this character, they would become as the savages—wild and uncivilised. They “don’t want to become like the animals,” they will say. They wish to remain “civilised,” and not return to a state of savagery and barbarism! There is no logic in this argument—indeed, no sense. Because a man lives upon fruits and nuts, it is, of course, no reason why he should return to a primitive state, _mentally_; indeed, there is far less evidence for this than there is that man becomes like the carnivorous animals by eating meat. There is evidence for that! But living upon fruits and nuts has no other effect than to elevate the tone and character of the body; to increase its energies and to render the mind clearer and more active. If these objectors to the fruitarian diet would only study physiology and human nature before passing any such absurd judgment upon the facts, their arguments would have more force—but then, in that case, they would not raise the arguments at all! Of course, this whole idea is conclusively proved to be erroneous by the facts in the case. There is one other point I should like to touch upon, though briefly, before passing on to the main argument of the book. The usual position with regard to food, and its functions in the body is this. Food has three functions: (1) The replacement of tissues which have been broken down as the result of the day’s work; (2) the maintenance of the bodily energy; and (3) the maintenance of the bodily heat. Now, in my former book,[1] I advanced a number of facts tending to show that food has but _one_ function—replacing broken-down tissue. It supplies no heat and no energy whatever to the body, at any time, or under any circumstances. Both the heat and the energy are due to another source altogether, and not to the food ingested.[2] I cannot enumerate the arguments in support of this position here; they will be found in full in the work referred to; but I would point out that, if this theory were true, it would cause us to modify very largely the views entertained as to the necessary amount of food required by the body. Now, a large percentage of the food eaten is supposed to create heat and energy, or at least liberate it, and is eaten for that express purpose. But if it be true that food has no other function than to supply the body with material for the rebuilding of its structures and tissues, it will be apparent that far _less_ food is necessary than is usually thought to be necessary by the physiologists; and this would account for the enormous differences in quantity said to be necessary by the various physiologists. The truth of the matter doubtless is, that the _smallest_ amount of food is that which is necessary, and all amounts over and above this are passed through the body at an expense of the vital energies, and to the detriment of the vital economy. However, I