Many men, even if possessing a lofty mind and a gentle heart, have asked themselves seriously, and more than once, whether they were capable of loving, unacquainted as they were with all that world of mysteries and passions which they found described in many books and heard from the mouths of some enamored friends. To those men my book, although I have striven to contain it within the limits of a physiological study, may seem an exaggeration, a caricature of nature. Now, all those men are petty and weak lovers. To them love is an intermittent prurience that begins at eighteen years and ends, perhaps, at forty, or fifty at the latest; a prurience that stands somewhere between pleasure and bother and which can be morally cured by only one medicine, woman. This medicine, so they say, is sometimes worse than the disease, and it is necessary to reflect at length and with great care whether preference should be given to that prurience which poets call "love," or to that other load which naturalists call "the female of man" and the courteous dictionaries "woman." When these eunuchs of the sentiment of love prefer the woman, they may find that this animated object, so like ourselves, is also tolerably pleasing and congenial, and a sweet and tender habit of benevolence may tie them to this companion whom they love, and truly love, in their own way, that is, calmly, prudently, suavely. These unhappy creatures have more than one reason to ask of themselves whether what they feel is love, and a thousand reasons to inquire of true lovers: "But tell me now, will you explain to me what this love is!" The moon radiates heat; frogs, too, develop heat: well, then, these gentlemen, too, do love!