It is true, indeed, after all these foregoing statements and concessions in regard to man's native character and the wholesomeness of a diet exclusively vegetable--and after admitting that the human body and mind can be fully and perfectly nourished and _developed_ on it, this distinguished writer goes on to say that it is still doubtful which diet--animal, vegetable, or mixed--is on the whole _most_ conducive to health, and strength--which is best calculated to avert or remove disease--whether errors in quantity or quality are most pernicious, etc. He says the solution of these and other analogous questions, can only be expected from experimental investigation. He proceeds to say-- "_Mankind are so averse to relinquish their favorite indulgences, and to desert established habits_, that we cannot entertain very sanguine expectations of any important discovery in this department. We must add to this, that there are many other causes affecting human health, besides diet. Before venturing to draw any inferences on a subject beset with so many obstacles, it would be necessary to observe the effects of a purely animal and a purely vegetable diet on several individuals of different habits, pursuits, and modes of life; to note their state, both bodily and mental; and to learn the condition of two or three generations fed in the same manner." Now, the only difference between this opinion and what I conceive to be the truth in the case is, that just such experimental investigations as those to which he refers have, to all intents and purposes, been already made; as, I trust, will be distinctly shown in the sequel of this work. DR. SALGUES. Dr. Salgues, Physician, and Professor of Anatomy, Physiology, etc., etc., to the Institute of France, some years ago wrote a book, entitled "Rules for Preserving the Health of the Aged," which contained many very judicious remarks on diet. There is nothing in the volume, however, which is decidedly in favor of a diet exclusively vegetable, unless it is a few anecdotes; and I have introduced his name chiefly as a sort of authority for those anecdotes. They are the following: "Josephus informs us that the Essenes were very long lived; many lived upward of one hundred years, solely from their simple habits and sobriety. Aristotle and Plato speak of Herodicus the philosopher, who, although of a feeble and consumptive habit, lived, in consequence of his sobriety, upward of one hundred years. Phabrinus, mentioned by Athenius, lived more than one hundred years, drinking milk only. Zoroaster, according to Pliny, remained twenty years in a desert, living on a small quantity of cheese only." THE AUTHOR OF "SURE METHODS," ETC. The British author of "Sure Methods of Improving Health and Prolonging Life," supposed by many to be the distinguished Dr. Johnson, speaks thus: