The other proposal is that taboos are the result of unconscious phenomena that are passed on (and this is called "Psychoanalytical approach"). Sigmund Freud provided an analysis of taboo behaviours. He highlighted strong subconscious motivations behind such prohibitions. In this system, described in his collection of essays "Totem and Taboo", Freud says there is a link between forbidden behaviours and the sanctification of objects to certain kinship groups. Freud also states that the only two "universal" taboos are that of incest and patricide, which formed the eventual basis of modern society.