Between institutions, as between organised beings, there is no sudden leap. Societies evolve slowly; it is by degrees that customs become refined, and that laws are formulated of a less and less brutal kind. It has been with marriage as with everything else. To the confusion of primitive bestial unions, when polygamy after the manner of chimpanzees prevailed, have succeeded sexual associations regulated by laws and customs. I have successively described these outlines or primitive forms of marriage, ending with polygamy, which itself is not incompatible with a somewhat advanced civilisation, but which generally, by its restrictions, soon develops a tendency towards monogamy. The abyss is not so very great that separates polygamic from monogamic marriage. As we have seen, primitive man, besides having a purely animal absence of modesty, has generally polygamic instincts, and nothing can be more natural, since he descends from anthropoid precursors, and the great monkeys are habitually polygamous. But the solidity of instincts, moral or immoral, is always in proportion to the duration of their rise. Now, during enormous chronological periods or cycles, in comparison with which the historic ages of humanity are but a moment, our nearest animal ancestors and our prehistoric percursors have, as far as it was possible, lived in a polygamic _régime_. It is therefore quite natural that most men, even in the present time, should be much inclined to polygamy, and that primitive societies should only have emerged slowly and imperfectly from it, while tempering monogamic marriage by polygamic palliatives. Of these palliatives the two principal ones still in use amongst the most civilised peoples are prostitution and concubinage, which last becomes a concubinate when legalised. II. _Prostitution._ It would certainly be out of place here to give a detailed history of prostitution. Having, besides, repeatedly spoken of it in the preceding chapters, I may now confine myself to recapitulating the chief traits of its evolution. In primitive societies, as we know, it is general, and in no way blamed. Free girls and women willingly sell themselves, and more often still, they are an article of traffic for their parents, like any other merchandise. No idea of shame as yet attaches to sexual unions considered in themselves. Prostitution is a simple barter which shocks no one, and venal love is merely restrained by respect for the property of another. Women who are already appropriated, or possessed by a man, are in principle respected, but solely by the same title as any other property. Their masters, their husbands, those who have bought or captured them, have a perfect right to hire them out to whomsoever they will, as the Australian husbands do, and as the Polynesian ones did.