Amazon.com description: Product Description: Three Contributions to the Theory of Sex, is a 1905 work by Sigmund Freud which advanced his theory of sexuality, in particular its relation to childhood. Freud's book covered three main areas: sexual perversions; childhood sexuality; and puberty. Freud began his first essay, on "The Sexual Aberrations", by distinguishing between the sexual object and the sexual aim — noting that deviations from the norm could occur with respect to both. The sexual object is therein defined as a desired object, and the sexual aim as what acts are desired with said object. His second essay, on "Infantile Sexuality", argues that children have sexual urges, from which adult sexuality only gradually emerges via psychosexual development. Looking at children, Freud identified many forms of infantile sexual emotions, including thumb sucking, autoeroticism, and sibling rivalry. In his third essay, "The Transformations of Puberty" Freud formalised the distinction between the 'fore-pleasures' of infantile sexuality and the 'end-pleasure' of sexual intercourse. He also demonstrated how the adolescent years consolidate sexual identity under the dominance of the genitals.