The kiss has grown in importance with the restrictions placed by civilisation on sexual activities. The more primitive the races, the more promiscuous they are and the less they kiss.
The kiss seems to have become among the more repressed and advanced races a displacement upward of the act of possession, a sublimation of intercourse. It is, next to sexual union, the closest contact which the male and female may attain.
Kisses and Electricity. If we adopt Crile's theory according to which the life stream is an electric current produced by the brain and constantly discharging itself, we may realise concretely the import of the kiss.
The physical union is probably the neutralisation of two electric currents, positive and negative, altho we do not know as yet what correspondence there is between sexes and opposite electric currents. Anyone familiar, however, with experiences in galvanotropism, some of which I have mentioned in Chapter II, will when reflecting upon the way in which the spermatozoon directs itself infallibly toward the egg, conclude that it is headed toward a strong electric current issuing from the woman's womb and ovaries.
The kiss is only a milder, less complete neutralisation of the currents issuing from two human beings.
If the kiss on the lips is preferred by lovers, it is because the moist mucus of the lips is a better conductor of electrical current than the skin. In very passionate kisses, the lovers' tongues play a double part, a symbolic part, representing the mother's nipple, and a physico-chemical part, securing a closer connection, like plug and socket in electric appliances.
In Anglo-Saxon fiction which does not countenance descriptions of lovers' embraces, a very passionate kiss is always symbolical of complete surrender. Physiologically this symbolism is quite accurate.
The temporary exhaustion which follows a protracted kiss is often equal to that following a lovers' embrace and this can be easily understood when we remember the protracted electrical discharge which must follow the contact of the conductive surfaces of the mucus of the lips.