It is important to notice that among mammals, as among men, conjugal fidelity is modified by the conditions of life. An animal belonging to a species habitually monogamic may easily change under the pressure of external causes and adopt polygamy, and, in some cases, polyandry. The shoveler duck, though normally monogamic, is said[96] to practise polyandry when males are in excess; two males being in constant and amicable attendance on the female, without sign of jealousy. Wild-ducks, again, which are strictly monogamous, good parents, and very highly developed in social qualities when in a wild state, become loosely polygamous and indifferent to their offspring under domestication. Civilisation, in this case, depraves the birds, as often it does men. But enough has now been said. We shall find later how far the facts we have learnt of the position of the female and the sexual relationship, as we have studied them in these examples from the animal kingdom, will apply to us and to our loves. We have now to study marriage and the family as it exists among primitive peoples. We shall find a close resemblance in the courtship customs and the sexual and familial associations to those we have seen to be practised by our pre-human ancestors. The same resemblance will persist when, lastly, we come to investigate the same institutions among civilised races, up to our own. Indeed, we may have to admit that, in some directions, love is not even yet as finely developed with us humans as it is among birds. It is in the loves of birds, as I believe, that we must seek hints to that evolution in fineness, which has still to come in our love. One thing more. It refers to the disputed question of the differentiation of the sexes by the action of love's-selection. It is a truth that I wish as strongly as I am able to emphasise. We cannot learn to know love's selective powers by enclosing its action within the narrow circle of our preconceived ideas. Instead of limiting its power we should extend it without hindrance of any form--to the female as well as the male; to the woman as to the man. We should regard nothing as impossible, no development of either sex too great to be accomplished, knowing that all progress is possible to love's power. Exceptional cases, then, irregularities, it may be, in sexual expression will henceforth no longer surprise us; they will find their place in the infinite order of life. Such examples may come to be regarded as filling in the chain; they form intermediate stages and also mark the reappearance of earlier manifestations of the sexual hunger. The new morality of love, which is having its birth amongst us to-day, will be deeper and wider than the old morality, because it will be founded on surer knowledge. FOOTNOTES: [50] Havelock Ellis, _Psychology of Sex_, Vol. VI. p. 422. [51] _Evolution of Sex_, p. 8. [52] _Animal Behaviour_, p. 265, quoted by Havelock Ellis, _Psychology of Sex_, Vol. III. p. 28.