With regard to
vision, we are in a somewhat better position. It is possible to estimate
the direction of the influence which certain visible characters exert on
sexual selection, and it is even possible to attempt their actual
measurement, although there must frequently be doubt as to the
interpretation of such measurements.

Two facts render it thus possible to deal more exactly with the influence
of vision on sexual selection than with the influence of the other senses.
In the first place, men and women consciously seek for certain visible
characters in the persons to whom they are attracted; in other words,
their "ideals" of a fitting mate are visual rather than tactile,
olfactory, or auditory. In the second place, whether such "ideals" are
potent in actual mating, or whether they are modified or even inhibited by
more potent psychological or general biological influences, it is in
either case possible to measure and compare the visible characters of
mated persons.

The two visible characters which are at once most frequently sought in a
mate and most easily measurable are degree of stature and degree of
pigmentation. Every youth or maiden pictures the person he or she would
like for a lover as tall or short, fair or dark, and such characters are
measurable and have on a large scale been measured. It is of interest in
illustration of the problem of sexual selection in man to consider briefly
what results are at present obtainable regarding the influence of these
two characters.

It has long been a widespread belief that short people are sexually
attracted to tall people, and tall people to short; that in the matter of
stature men and women are affected by what Bain called the "charm of
disparity." It has not always prevailed. Many centuries ago Leonardo da
Vinci, whose insight at so many points anticipated our most modern
discoveries, affirmed clearly and repeatedly the charm of parity. After
remarking that painters tend to delineate the figures that resemble
themselves he adds that men also fall in love with and marry those who
resemble themselves; "_chi s'innamora voluntieri s'innamorano de cose a
loro simiglianti_," he elsewhere puts it.[171] But from that day to this,
it would seem Leonardo's statements have remained unknown or unnoticed.
Bernardin de Saint-Pierre said that "love is the result of contrasts," and
Schopenhauer affirmed the same point very decisively; various scientific
and unscientific writers h