John Calvin Commentary Genesis 3:18

"thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field;" — Genesis 3:18 (ASV)

Thorns also and thistles shall it bring forth. He discusses more extensively what he has already alluded to, namely, that obtaining the fruits of the earth would involve labor and trouble. And he gives the reason that the earth will not be the same as it was before, when it produced perfect fruits; for he declares that the earth would lose its fertility and bring forth briers and harmful plants.

Therefore, we may know that whatever unwholesome things are produced are not natural fruits of the earth, but corruptions that originate from sin. Yet it is not for us to argue with the earth for not responding to our wishes and the labors of its cultivators, as if it were maliciously thwarting our purpose; but in its sterility, let us recognize God's anger and mourn over our own sins.

It has been falsely maintained by some that the earth is exhausted by the long passage of time, as if constantly producing crops has wearied it. Those who acknowledge that the increasing wickedness of people gradually diminishes and impairs God's remaining blessing think more correctly; and certainly, there is a danger that, unless the world repents, a great part of humanity will soon perish through hunger and other dreadful miseries.

The words immediately following, You shall eat the herb of the field, are interpreted too strictly (in my judgment) by those who think that Adam was, as a result, deprived of all the fruits that he had previously been permitted to eat. God intends nothing more than that he would be deprived of his former delicacies to such an extent that he would be compelled to also use the herbs originally intended only for animals.

For the way of life first appointed to him, in that happy and delightful abundance, was far more refined than it later became. God, therefore, describes a part of this poverty by the word herbs, just as if a king were to send one of his attendants from the main table to one that was common and lowly; or as if a father were to feed a son who had offended him with the coarse bread of servants. This is not to say that God forbids humanity all other food, but that He reduces much of His customary generosity.

This, however, might be taken as added for consolation, as if it had been said, ‘Although the earth, which ought to be the mother of good fruits only, is covered with thorns and briers, still it shall yield to you sustenance by which you may be fed.’