I certainly do not claim to have studied all the pure and impure sources of love, but I would feel satisfied if I had touched upon the most important ones, and outlined the genealogy of this sentiment. In an analytical work, however great may be the care exercised in order not to detach adherent things, it is next to impossible to avoid breaking some fiber or destroying anything. It frequently occurs that the source of love is not one, but double, or is formed by the collecting of various streamlets, so that it would be difficult to state whether the new-born is a legitimate son or a bastard. A slight but sincere sympathy may be associated with great vanity, but the desire for revenge may, fortunately for us, fall in with a warm and violent affection. Thus, lust, vanity, compassion, gratitude, may meet at the same time and fecundate a love which later may flow limpid and pure in its bed, although its source was an impure, muddy stream. Sometimes a human being loves another not for the latter's sake, but out of a strange resemblance which the latter bears to a person long loved and, perhaps, already lost; thus it happens that one may love the daughter after having loved the mother; and there have been cases in which one has loved even three successive generations. The excessive disproportion in the age of the lovers, a certain mummy effluvium exhaled even by the most carefully embalmed bodies, gives to those loves a character that induces me to place them at least on the frontiers that separate physiology from pathology; I would, therefore, term them "physio-pathological."