In the use of the beginning of sexual intercourse, as a line of demarcation between periods of human existence, it would seem that a most natural and rational selection were made. As a proof of this, it is but necessary to call to mind the large number of barbaric and semi-civilized peoples who observe some initiatory rites or mysteries connected with the arrival of the individual at puberty or nubility, which with them is, to all intents and purposes, the same as, if not absolutely identical with, the beginning of sexual indulgence. Under our civic law, it is at this time that, through marriage, the human being assumes his full responsibilities, and, by the beginning of an independent family relation, becomes an integral, co-ordinate member of the state. It is at this "stress and storm" period that the real work of life--the fruition of existence--takes place. Beginning with the intimate association with another human being, whose rights and privileges are so interwoven with our own that it is frequently a hard matter to respect them without becoming distant, tolerating the idiosyncrasies, and lauding the virtues, in such a way that the former are diminished, while the latter are increased; trying to anticipate the wants and wishes of the other so that they may be gratified--not for their own satisfaction, primarily, but for our own; seeing the pleasures of sensuality transmuted in the crucible of pain into the gold of a new existence; feeling the supplementary affection and interest, which, for the want of a better name, we call parental love, and, as the offspring grow older, the pride and elation which comes with their achievements; standing at last beside the grave, crushed with grief, raving like Macbeth in despair, or inspired with a transcendental insanity like Richter's--these all are the vicissitudes of mature human life, when at its best. But, great and varied as they are, we find them, in fact, very closely fused together; and like all life-processes, they take place at a comparatively slow rate, so that before we are aware, we have arrived at the beginning of senile degeneration.