Summa summae S. Thomae sive compendium theologiae

[I answer in the affirmative. In the state of innocence men would have been born in original justice, and consequently in sanctifying grace, which is the root of original justice¹.

Proof 1°. Naturally man generates his like according to species. Hence whatever accidents follow upon the nature of the species, in these it is necessary that children resemble their parents, unless there be an error in the operation of nature, which would not have occurred in the state of innocence. But in individual accidents it is not necessary that children resemble their parents. Now original justice, in which the first man was created, was an accident of the nature of the species, not as though caused from the principles of the species, but only as a certain good divinely given to the whole nature². Therefore.

Proof 2°. Original justice was a gift divinely granted to the whole human nature. Therefore. — Proof of the antecedent. Opposites are of one genus. But original sin, which is opposed to original justice, is a sin of nature; hence it is transmitted from parents to their posterity³. Therefore.

And this is what Anselm teaches, saying in the book de Conceptu Virginis, c. 10: « As soon as they had a rational soul, those whom man would beget, if he had not sinned, would be just. »

You will ask whether in the state of innocence men would have been born confirmed in justice.

I answer in the negative⁴.

Proof. Children at their birth would not have had more perfection than their parents in the state of generation. But the parents, so long as they were begetting, would not have been confirmed in grace. Therefore. — Proof of the minor. A rational creature, by the ordinary law and apart from a special privilege, is not confirmed in justice except through the clear vision of God, to which, once seen, it cannot but cleave, since He Himself is the essence of goodness, from which, once possessed, no one can be turned away, since nothing is desired and loved except under the note of good. Therefore.

I said, apart from a special privilege, such as was granted to the blessed and immaculate Virgin Mary.]