In the early centuries of the Christian era, there was no certainty about the time when human life began and for a long time the debate was very active because it was extremely important to have a basis to know whether abortion was murder or not.
Augustine of Hippo (354-430 a.C.) criticized the abortion because he believes that breaks the compulsory link between sex and reproduction, but even so, exposes the need to differentiate between the “seed conceived” (conceptus fetus), that has no vitality a human being (prius interire quam vivere), the state when the fetus in the uterus moves towards human life ( aut si in utero jam vivebat), and even of being born. Augustine also states that “the act of abortion is not considered murder, because you can not even claim to have a living soul in a body that lacks sensation, and still has not formed the meat and is not endowed with senses”.
He argued that human life began, for both sexes at 45 days gestation, which was very little discordant with the old interpretations of Hippocrates (460-377 b.C.) who taught that this principle was the case at 35 days.
Nine centuries later, Thomas Aquinas (1225-1274) presented more explicitly, the idea that God would infuse the human soul only when encountering a “matter ready”, a body with a level of organic development that allows for the soul. According to his interpretation, the soul enters the body 40 days after conception in the case of males and 80 days later in the case of women. His ideas were very supportive in the philosophy of Aristotle (384-322 b.C.), in the biological knowledge of Ibn Sina (Avicenna, 980-1037) and the thesis of Ibn Rushd (Averroes, 1126-1198) who claimed, with a real authority of Aristotle, that reason always prevails over religion. In the same period coinciding with Thomas Aquinas, Albertus Magnus (1206-1280) argues that the soul is infused by God, in the man at forty days and the woman at ninety.
In the European Renaissance, the Jesuit Luis de Molina (1535-1600) argues that in practice, the Holy See supports the fetus only after fifty days has a rational soul. Later, the physician Thomas Fienus (1567-1631) author of “De animatione foetus ” published in 1620, thinks the infusion of the soul occurs within a few days after conception, a position that was defended and propagated by the bishop Alphonsus Liborio (1696-1787), regarded doctor of the church for his writings on moral.
The belief that the infusion of the soul does not occur until delivery was always unacceptable to the Christian ethical tradition. Joannes Caramuel Lobkowitz (1606-1682), Spanish philosopher and theologian, says emphatically that not only unlikely but also intolerable.
In 1869 Pope Pius IX in the Minutes Apostolicae Sedis, the official newsletter of the Apostolic See, promulgates that hominization is not a process accepted by Catholicism, without further arguments decreed that the body and soul together in the very act of conception and therefore abortion, at any time or circumstance, is a murder for the Catholic Church deserves excommunication. This is an apostolic official position, is not considered an article of faith nor is there a theological foundation strong enough to sustain a fertilized egg or embryo to be considered as persons.
Only in the twentieth century is can confirm in an objective way the right insight of Hippocrates and Augustine of Hippo. Doing an ultrasound real time to a woman with symptoms of pregnancy, it is possible to see the heartbeat of the embryo after 35 days of gestation, clinically considered as the first evidence of gestational activity is interpreted as confirmation of the start of a new life in the uterine cavity of women. In the absence of heartbeats to 45 days, the diagnosis is that the implanted gestational sac did not meet the biologic conditions necessary for human life is revealed.