The following treatise is a translation, revised and enlarged, of my “Thése pour le Doctorat”, which, under the title “De l’Alimentation Vegetale chez l'Homme”, I presented in the month of July, 1880, at the Faculté de Médecine of Paris on completing my medical studies and taking my degree. The original thesis was published in Paris in the French language, and subsequently translated into German and issued with illustrative notes and other additions by Dr. A. Aderholdt. Encouraged by the success obtained by these two editions, and by the favourable notices they elicited from various foreign scientific and popular critics, I offer the present work to English readers, confident of a kindly welcome from the friends of the reform I advocate, and hopeful of a serious and intelligent hearing from those who as yet are strangers to the merits of that reform. The French and German editions of this treatise include an Appendix, containing short notices and citations from the works of the chief exponents and exemplars of the Pythagorean system of diet. In the present volume this Appendix is suppressed in favour of a forthcoming Catena of Authorities Denunciatory or Depreciatory of the Practice of Flesh-Eating, by a Graduate of Cambridge; an excellent and ample compendium to which the reader is referred. That I have dwelt chiefly on the aspects, physical and social, of my subject, and touched but lightly on those moral and philosophical, is not, assuredly, because I regard these last as of lesser importance, but because their abstruse and recondite nature renders them unsuitable to a work intended for general reading. Finally, if any into whose hands this book may fall, should be inclined to think me over-enthusiastic, or to stigmatise my views as “Utopian”, I would ask him seriously to consider whether “Utopia” be not indeed within the realisation of all who can imagine and love it, and whether, without enthusiasm, any great cause was ever yet won for our race. Man is the master of the world, and may make it what he will. Into his hands it is delivered with all its mighty possibilities for good or evil, for happiness or misery. Following the monitions and devices of the sub-human, he may make of it —what indeed for some gentle and tender souls it has already become—a very hell; working with God and Nature, he may reconvert it into Paradise.