Intersexes in the human species--not only the extreme pathological cases represented by the so-called "hermaphrodites," but also merely masculine women and effeminate men--have been the subject of serious remarks as well as literary gibes from the earliest times. The Greeks called these people _urnings_. Schopenhauer was interested in the vast ancient literature and philosophy on this subject. The 19th century produced a copious psychological treatment of warped or reversed sexual impulses by such men as Moll, Krafft-Ebing and Havelock Ellis. Otto Weiniger[10] collected a mass of this philosophy, literature, psychology, folklore and gossip, tied it together with such biological facts as were then known (1901) and wove around it a theory of sex _attraction_.[A] The same material was popularized by Leland[11], Carpenter[12] and W.L. George[13] to support quite different views. [Footnote A: NOTE: Weiniger thought he could pick, merely by observing physical type, people who would be sexually attracted to each other. There is much ground for scepticism about this. To begin with, the biological experiments indicate that intersexes are peculiarly likely to appear where two or more races are mixed. So far, there is no exact knowledge about the amount or kind of sex difference in each race. As Bateson remarks (Biol. Fact & the Struct. of Society, p.13), one unversed in the breeds even of poultry would experience great difficulty and make many mistakes in sorting a miscellaneous group of cocks and hens into pairs according to breed. If this is true in dealing with pure breeds, "in man, as individuals pure-bred in any respect are very rare, the operation would be far more difficult." In the human species sexual attraction also obviously depends upon many factors which are not purely biological; it is rather a complicated sentiment than an instinct.]