In religion and philosophy, ensoulment is the moment at which a human or other being gains a soul. Some belief systems maintain that a soul is newly created within a developing child and others, especially in religions that believe in reincarnation, that the soul is pre-existing and added at a particular stage of development. In the time of Aristotle, it was widely believed that the human soul entered the forming body at 40 days (male embryos) or 90 days (female embryos), and quickening was an indication of the presence of a soul. Other religious views are that ensoulment happens at the moment of conception; or when the child takes the first breath after being born;<ref name="google.com">[http://www.google.com/search?q=Schiff+%22response+to+Antoninus%22&btnG=Search+Books&tbm=bks&tbo=1 Daniel Schiff, Abortion in Judaism']' (Cambridge University Press 2002 ), p. 42, footnote 38</ref> at the formation of the nervous system and brain; at the first detectable sign of brain activity; or when the fetus is able to survive independently of the uterus (viability). The concept is closely related to debates on the morality of abortion as well as the morality of contraception. Religious beliefs that human life has an innate sacredness to it have motivated many statements by spiritual leaders of various traditions over the years. However, the three matters are not exactly parallel, given that various figures have argued that some kind of life without a soul, in various contexts, still has a moral worth that must be considered. Ancient Greeks Among Greek scholars, Hippocrates (c.460 – c.370 BC) believed that the embryo was the product of male semen and a female factor. But Aristotle (384 – 322 BC) held that only male semen gave rise to an embryo, while the female only provided a place for the embryo to develop, (a concept he acquired from the preformationist Pythagoras). Aristotle believed a fetus in early gestation has the soul of a vegetable, then of an animal, and only later became "animated" with a human soul by "ensoulment". For him, ensoulment occurred 40 days after conception for male fetuses and 90 days after conception for female fetuses,ReligiousTolerance.org the stage at which, it was held, movement is first felt within the womb and pregnancy was certain.Norman M. Ford, When Did I Begin? Conception of the Human Individual in History, Philosophy and Science (Cambridge & New York, Cambridge University Press ), p. 28 This is called epigenesis, which is "the theory that the germ is