7 They do not, however, stop here; even our acts, where each one feels his will ruling, I mean, the practice of virtue or of vice, depend, according to them, on the influence of celestial bodies. It would be ridiculous seriously to refute such an error, but, as it holds a great many in its nets, perhaps it is better not to pass it over in silence. I would first ask them if the figures which the stars describe do not change a thousand times a day. In the perpetual motion of planets, some meet in a more rapid course, others make slower revolutions, and often in an hour we see them look at each other and then hide themselves. Now, at the hour of birth, it is very important whether one is looked upon by a beneficent star or by an evil one, to speak their language. Often then the astrologers do not seize the moment when a good star shows itself, and, on account of having let this fugitive moment escape, they enrol the newborn under the influence of a bad genius. I am compelled to use their own words. What madness! But, above all, what impiety! For the evil stars throw the blame of their wickedness upon Him Who made them. If evil is inherent in their nature, the Creator is the author of evil. If they make it themselves, they are animals endowed with the power of choice, whose acts will be free and voluntary. Is it not the height of folly to tell these lies about beings without souls? Again, what a want of sense does it show to distribute good and evil without regard to personal merit; to say that a star is beneficent because it occupies a certain place; that it becomes evil, because it is viewed by another star; and that if it moves ever so little from this figure it loses its malign influence.
But let us pass on. If, at every instant of duration, the stars vary their figures, then in these thousand changes, many times a day, there ought to be reproduced the configuration of royal births. Why then does not every day see the birth of a king? Why is there a succession on the throne from father to son? Without doubt there has never been a king who has taken measures to have his son born under the star of royalty. For what man possesses such a power? How then did Uzziah beget Jotham, Jotham Ahaz, Ahaz Hezekiah? And by what chance did the birth of none of them happen in an hour of slavery? If the origin of our virtues and of our vices is not in ourselves, but is the fatal consequence of our birth, it is useless for legislators to prescribe for us what we ought to do, and what we ought to avoid; it is useless for judges to honour virtue and to punish vice. The guilt is not in the robber, not in the assassin: it was willed for him; it was impossible for him to hold back his hand, urged to evil by inevitable necessity. Those who laboriously cultivate the arts are the maddest of men. The labourer will make an abundant harvest without sowing seed and without sharpening his sickle. Whether he wishes it or not, the merchant will make his fortune, and will be flooded with riches by fate. As for us Christians, we shall see our great hopes vanish, since from the moment that man does not act with freedom, there is neither reward for justice, nor punishment for sin. Under the reign of necessity and of fatality there is no place for merit, the first condition of all righteous judgment. But let us stop. You who are sound in yourselves have no need to hear more, and time does not allow us to make attacks without limit against these unhappy men.
Source: Nine Homilies of Hexaemeron (New Advent)