Chapter 28 [XIV.]— Augustine's Answer to This Argument. Its Dealing with Scripture.
Now to this lengthy statement of his we have to say in answer, that, in the passages which he has quoted from the sacred writings, there is nothing said about that shameful lust, which we say did not exist in the body of our first parents in their blessedness, when they were naked and were not ashamed. The first passage from the apostle was spoken of the seeds of grain, which first die in order to be quickened. For some reason or other, he was unwilling to complete the verse for his quotation.
All he adduces from it is: “You fool, that which you sow is not quickened;” but the apostle adds, “except it die.” This writer, however, so far as I can judge, wished this passage, which treats only of grain seeds, to be understood of human seed, by such as read it without either understanding the Holy Scriptures or recollecting them. Indeed, he not merely curtailed this particular sentence, by omitting the clause, “except it die,” but he omitted the following words, in which the apostle explained of what seeds he was speaking; for the apostle adds: “And that which you sow, you sow not that body which shall be, but the bare grain, it may chance of wheat, or of some other grain.” This he omitted, and closed up his context with what the apostle then writes: “But God gives it a body as it has pleased Him, and to every seed its own body;” just as if the apostle spoke of man in cohabitation when he said, “You fool, that which you sow is not quickened,” with a view to our understanding of human seed, that it is quickened by God, not by man in cohabitation begetting children.
For he had previously said: “Sexual pleasure does not complete the entire process of man's making, but rather presents to God, out of the treasures of nature, material with which He vouchsafes to make the human being.” He then added the quotation, as if the apostle affirmed as follows: You fool, that which you sow is not quickened—quickened, that is, by yourself; but God forms the human being out of your seed. As if the apostle had not said the intermediate words, which this writer chose to pass over; and as if the apostle's aim was to speak of human seed thus: “You fool, that which you sow is not quickened; but God gives to the seed a body such as pleases Him, and to every seed its own body.”
Indeed, after the apostle's words, he introduces remarks of his own to this effect: “If, therefore, God has assigned to human seed, as to everything else, its own proper body, which no wise or pious man will deny;” quite as if the apostle in the passage in question spoke of human seed.
Source: On Marriage and Concupiscence (New Advent)