A whole volume could be written on the forms of flirtation, which is the indispensable expression of all sexual desire. Among engaged couples it assumes a legal character and even a conventional form. The way in which barmaids flirt with their customers is also somewhat conventional, although in quite a different way. In society, flirtation is generally seasoned with more Attic salt, whether it is not allowed to exceed certain limits, or whether it leads to free liaisons after the manner of the Greek hetaira. In the country, among peasant girls and boys it takes a grosser form, if not more sensual, than among the cultivated classes; in the latter, language takes the principal part. Among rich idlers in watering places, large hotels, and even in some sanatoriums, flirtation takes a dominant place and constitutes, in all its degrees, the chief occupation of a great number of the visitors. It grows like a weed wherever man has a monotonous occupation or suffers from the ennui of idleness. In certain individuals, flirtation takes the place of coitus from the sensual, and love from the sentimental point of view. There are modern crazy natures who spend their existence in all kinds of artificial excitation of the senses, creatures of both sexes incapable of a useful action. As a momentary and transient expression of all the necessities of love, flirtation has a right to existence; but, when cultivated on its own account and always remaining as flirtation, it becomes a symptom of degeneration or sexual depravity, among idle, crazy and vicious persons of all kinds. FOOTNOTES: [2] The terms _grisette_ and _lorette_ are now obsolete, and the names given to this class of women constantly varies. I shall, nevertheless, employ them in the course of this work because they clearly define certain special varieties of remunerated concubinage. CHAPTER V LOVE AND OTHER IRRADIATIONS OF THE SEXUAL APPETITE IN THE HUMAN MIND =Generalities. Jealousy.=--We have seen that the mechanism of the appetites consists in instincts inherited from our animal ancestors by mnemic engraphia and selection, and that it is situated in the primordial or lower cerebral centers (basal ganglia, spinal cord, etc.). In some of the lower animals we already find other instinctive nervous reactions which constitute the indirect effects or derivatives of the sexual appetite. The most evident of these is _jealousy_, or the feeling of grief and anger produced in an individual when the object of his sexual appetite is disputed by another individual of the same sex. Jealousy may also arise from other instincts, such as those of nutrition, ambition, etc.; but it forms one of the most typical complements of the sexual appetite, and leads, as we know, to furious combats, especially between males, sometimes also between females.