imal life. After these have been
considered, not only in themselves, but in the relation they bear to
the higher forms which developed from them, we shall be in a surer
position to re-ascend the ladder of life. We shall come to understand
the biological significance of love--something of the complexity and
beauty and force of the passions that we have inherited. We shall find
also the causes, so important to us, which led to the reversal of the
early superiority of the female in size and often in function,
replacing it by the superiority of the male. Then, and then only,
shall we be ready to approach the difficult problems of the sexual
differences which have persisted, separating women from men among
human races, and to estimate if these differences are to be considered
as belonging essentially to the female and the male, or whether they
have arisen through special environmental causes.

If we look back anew to the very start of sexuality, where two cells
flow together, thereby to continue life, we find the very simplest
expression of the sex-appetite. There is what may be called
instinctive physical attraction, and the whole process is very much a
satisfaction of protoplasmic hunger.[39] Now it was, of course, a long
step from this incipient cell-union to the varied function of sex in
animal life, and it was a long process from these to the yet more
complex manifestation of the love-passion among men. But in reality
the source of all love is the same; throughout the entire relations of
the sexes we find this cell-hunger instinct; in every case, it matters
not how fine and ennobling the love may be, the single, original,
impelling motive is the union of two cells--the male element and the
female driven to seek one another to continue life. I find it
necessary to insist on this physical basis of all love. Women are so
apt to go astray. It is one of the vicious tendencies of the female
mind to think that the needs of sex are something to be resisted. Let
us face the truth that this great force of love has its roots fastened
in cell-hunger, and it dies when its roots are cut away.

It is evident that at first this sex-appetite cannot have been
purposive, but acted subconsciously by a kind of interaction between
the want of the organism and its power of function. Even in many
complex multicellular organisms the liberation of the sex-elements
continues very passive; and although the differentiation of the
sexual-cells is