A few weeks ago I discussed the pro-life position in the DBTS chapel, including the biblical perspective of when human life begins—at conception. I found it interesting to see John Calvin promoting the view that human life begins at conception in an article he wrote against astrology: John Calvin, trans. by Mary Potter, “A Warning Against Judicial Astrology” Calvin Theological Journal, 18 (1983): 157-189.
In showing the flaw in assuming that one’s destiny is connected to the position of the celestial bodies at one’s birth, he reasons that the real concern should be their position at the point of conception. Calvin clearly assumes that a person’s existence begins at conception rather than birth, though neither are truly effective at predicting a person’s nature through astrology.
“Our mathematicians (of whom I am speaking) base their judgments about a person on the hour of his birth. However, I say on the contrary that it is the hour of conception which should be considered, which is more often than not unknown because mothers do not always carry their children for fixed terms of pregnancy. What reply can they make, if they are convinced by reason that the stars do not have as great a power to imprint certain qualities on a person at birth as at conception?” 168
“Suppose we take two men of quite different natures, each having a wife whose nature is equally diverse from the other’s. If these two women were to conceive at the same time and even give birth simultaneously, what would ordinarily happen is that each child born would take its complexion from its own mother and father rather than from the position of the stars, which is the same for both of them.” 169