The Divine Institutes

A question also may arise respecting this, whether the soul is produced from the father, or rather from the mother, or indeed from both. But I think that this judgment is to be formed as though in a doubtful matter. For nothing is true of these three opinions, because souls are produced neither from both nor from either. For a body may be produced from a body, since something is contributed from both; but a soul cannot be produced from souls, because nothing can depart from a slight and incomprehensible subject. Therefore the manner of the production of souls belongs entirely to God alone.

…as Lucretius says. For nothing but what is mortal can be generated from mortals. Nor ought he to be deemed a father who in no way perceives that he has transmitted or breathed a soul from his own; nor, if he perceives it, comprehends in his mind when or in what manner that effect is produced.

From this it is evident that souls are not given by parents, but by one and the same God and Father of all, who alone has the law and method of their birth, since He alone produces them. For the part of the earthly parent is nothing more than with a sense of pleasure to emit the moisture of the body, in which is the material of birth, or to receive it; and to this work man’s power is limited, nor has he any further power. Therefore men wish for the birth of sons, because they do not themselves bring it about. Everything beyond this is the work of God,—namely, the conception itself, and the moulding of the body, and the breathing in of life, and the bringing forth in safety, and whatever afterwards contributes to the preservation of man: it is His gift that we breathe, that we live, and are vigorous. For, besides that we owe it to His bounty that we are safe in body, and that He supplies us with nourishment from various sources, He also gives to man wisdom, which no earthly father can by any means give; and therefore it often happens that foolish sons are born from wise parents, and wise sons from foolish parents, which some persons attribute to fate and the stars. But this is not now the time to discuss the subject of fate. It is sufficient to say this, that even if the stars hold together the efficacy of all things, it is nevertheless certain that all things are done by God, who both made and set in order the stars themselves. They are therefore senseless who detract this power from God, and assign it to His work.

He would have it, therefore, to be in our own power, whether we use or do not use this divine and excellent gift of God. For, having granted this, He bound man himself by the mystery of virtue, by which he might be able to gain life. For great is the power, great the reason, great the mysterious purpose of man; and if any one shall not abandon this, nor betray his fidelity and devotedness, he must be happy: he, in short, to sum up the matter in few words, must of necessity resemble God. For he is in error whosoever judges of man by his flesh. For this worthless body with which we are clothed is the receptacle of man. For man himself, can neither be touched, nor looked upon, nor grasped, because he lies hidden within this body, which is seen. And if he shall be more luxurious and delicate in this life than its nature demands, if he shall despise virtue, and give himself to the pursuit of fleshly lusts, he will fall and be pressed down to the earth; but if (as his duty is) he shall readily and constantly maintain his position, which is right for him, and he has rightly obtained,—if he shall not be enslaved to the earth, which he ought to trample upon and overcome, he will gain eternal life.