Almighty God and infused into the embryo at the very moment of
conception. Still, as St. Gregory could not prove the certainty of his
doctrine, it was opposed by the majority of the learned.

The Schoolmen of the Middle Ages, while condemning abortion from the
time of conception, preferred the opinion of Aristotle, that the
rational soul is not infused till the fœtus is sufficiently developed to
receive it. The embryo lived first, they taught, with a vegetable life;
after a few days an animal soul replaced the vegetative principle; the
human soul was not infused into the tiny body till the fortieth day for
a male, and the eightieth day for a female child. All this sounds very
foolish now; and yet we should not sneer at their ignorance; had we
lived in their times, we could probably have done no better than they.

It was not till 1620 that Fienus, a physician of Louvain, in Belgium,
published the first book of modern times that came near the truth. He
maintained that the human soul was created and infused into the embryo
three days after conception. Nearly forty years later, in 1658, a
religious priest, called Florentinius, wrote a book in which he taught
that, for all we know, the soul may be intellectual or human from the
first moment of conception; and the Pope's physician Zachias soon after
maintained the thesis as a certainty that the human embryo has from the
very beginning a human soul.

Great writers applauded Fienus and his successors; universities favored
their views; the Benedictines, the Dominicans, and the Jesuits supported
them. Modern science claims to have proved beyond all doubt that the
same soul animates the man that animated the fœtus from the very moment
of conception. The "Medical Jurisprudence" of Wharton and Stillé quotes
Dr. Hodge of the Pennsylvania University as follows (p. 11): "In a most