Much has been written, good, bad and indifferent, on the diverse matters which enter into the laws and relations of sex. Part is the product of unlearned quacks, whose motives and qualifications I do not care to scrutinize at present; part, that of certain dry-as-dust clinicians, whose facts, when they give us any, are utterly devoid of the faintest charm of literary expression; but a goodly portion, fortunately, in recent years particularly, of genuine literary and psychological reasoners, whose work I cannot hope to improve; except by a, perhaps, more systematic and rational method of classification and treatment.

In this connection I would mention first the splendid treatise of Krafft-Ebing,1 as only too severely technical for the average reader; that of Have-lock Ellis,' as lacking grievously in order!y arrangement; both, however, being veritable mines of scientific information; that of Ulrichs,* as an argument, pro domo, in favor of homosexuality; that of Moll,* while the best of all on sexual inversion, as too exclusively psychological; that of Chevalier,' as lacking somewhat in critical perception; though in the main copious and correct; and that of FeYe\7 which I regard as, in the ground covered, the completest and most satisfactory work on the subject yet written.

Whether the faults enumerated are corrected, or the undoubted great merits of these writers even approached, in the following work, the reader must detennine. It is my hope, however, while retaining all that is most valuable in the authors named, to present the facts in such continuity of form as to render my work a more readily accessible medium of professional reference; and, in collating from various other sources whatever additional information more recent inquiry may have brought to light, together with the results of personal observation, and the passing reflections which they may suggest, and by the exclusion, as far as possible, of scientific technicalities, to make my work more easily intelligible to the lay-reader who may desire—as all should—to enlighten himself, or herself, on the immutable system of laws which not only underlies this life, but upon the rational observance of which depend, more largely, perhaps, than commonly supposed, our hopes and expectations of a fuller and nobler one hereafter.