Humanity is ever seeking the Reality--the Noumenon, which we intuitively postulate as behind the phenomena of Nature. The institution of marriage, coming down to us through all the ages, side by side with the mystery of sex, and incorporated with the sex-mystery into every form and system of religious rites and ceremonials among all peoples, would seem to have a place in human ethics, as substantial and as permanent as the germ of life itself. Indeed, the institution of marriage, in its first stages of evolution, obtains in the animal kingdom, where selection in a great variety of forms is common. And it must be confessed that here we find the same tendency to change and variation, both in regard to the individual and the family species, as we have in the human family. Polyandry, polygamy, and monogamy, have been general among some animals while among others only one form of mating has been the rule. Strange to say, sex promiscuity is not at all general among the animals, though polygamy is common. The adoption of polygamy is obviously due to one of two things, or possibly, to be more specific, to both. First, because the percentage of deaths among the males is greater than among the females; this applies to animal life, both wild and domestic. In wild life, because of frequent combats; in domestic life, because the females are kept for breeding while the males are slaughtered for food. The second reason is because the female is seldom as virile as the male, and to this is also added the debilitating effect of bearing and rearing the young, the necessity for which must have manifested itself very early among the various families, from motives of self-protection, if from nothing higher, since victory evidently favored the numerically strong. In bird-life, especially, where love is so vital a part of their life, and so beautifully expressed, monogamy is the rule, and in some species, like that of the robin, a certain aristocracy seems to exist, preventing intercourse with any other family. The robin will mate only with a robin, and not infrequently mates for life; which is to say that should one die, the other refuses to mate again. It is claimed that the bald-headed eagle never varies from monogamy. A mate once chosen, the union lasts until the death of either partner. It does not follow from this, however, that the bald-headed eagle is a creature of a superior moral conscience. It may be that he is guided in his selection of a conjugal mate by an intuitional power undeveloped by other types of life, or, which is far more probable, it may be that his sexual nature is easily satisfied and that he has no temperamental affinities or repulsions, in which event force of habit would be the strongest actuating power. This explanation is in keeping with the eagle character.