brought into existence (by successive accretions), and not merely developed, in the process of reproduction," in contrast to the theory of preformation, which asserts the "supposed existence of all the parts of an organism in rudimentary form in the egg or the seed;" modern embryology, which finds both that an organism begins with an inherited genetic code and that embryonic stem cells can develop epigenetically into a variety of cell types, may be seen as supporting a balance between the views. Stoicism maintained that the living animal soul was received only at birth, through contact with the outer air, and was transformed into a rational soul only at fourteen years of age. Epicureanism saw the origin of the soul (considered to consist of only a small number of atoms even in adults) as simultaneous with conception. Pythagoreanism also considered ensoulment to occur at conception. Christianity Historical development From the 12th century, when the West first came to know more of Aristotle than his works on logic,James Edward McClellan, Harold Dorn, Science and Technology in World History (Johns Hopkins University Press 2006 ), p. 184 mediaeval declarations by Popes and theologians on ensoulment were based on the Aristotelian hypothesis. Aristotle's epigenetic view of successive life principles ("souls") in a developing human embryo—first a vegetative and then a sensitive or animal soul, and finally an intellective or human soul, with the higher levels able to carry out the functions also of the lower levels—was the prevailing view among early Christians, including Tertullian, Augustine, and Jerome. Lars Østnor says this view was only "presaged" by Augustine, who belongs to a period later than that of early Christianity. According to David Albert Jones, this distinction appeared among Christian writers only in the late fourth and early fifth century, while the earlier writers made no distinction between formed and unformed, a distinction that Saint Basil of Caesarea explicitly rejected. While the Hebrew text of the Bible only required a fine for the loss of a fœtus, whatever its stage of development, the Greek Septuagint (LXX) translation of the Hebrew text, a pre-Christian translation that the early Christians used, introduced a distinction between a formed and an unformed fœtus and treated destruction of the former as murder. It has been commented that "the LXX could easily have been used to distinguish human from non-human fœtuses and homicidal from non-homicidal abortions, yet the early Christians, until the