John Calvin Commentary Jeremiah 4:3

"For thus saith Jehovah to the men of Judah and to Jerusalem, Break up your fallow ground, and sow not among thorns." — Jeremiah 4:3 (ASV)

The Prophet still pursues the same subject, for he reproves the hypocrisy of the Israelites because they sought to discharge their duty towards God only by external ceremonies, while their hearts were full of deceit and every kind of impiety and wickedness. For this reason, he says that God required this from the Jews: to plough again the fallow, and not to sow among thorns.

It is a very suitable comparison, for Scripture often compares us to a field when it represents us as God’s heritage. We have been chosen by God as a special people for this purpose: that he may gather fruit from us, as a farmer gathers produce from his fields.

Indeed, we can add nothing to what God is, but there is a fruit that he demands, so that our whole life is to be devoted to his glory. God, then, would not have us be idle and fruitless, but rather bring forth some fruit. But what do hypocrites do?

They sow; that is, they show some concern, yes, they pretend great ardor when God exhorts them to repent or when he invites them. They then make a great bustle, yet they spoil everything with their own adulterations, just as if someone scattered seed among thorns; but it will be of no use to cast seed among thorns in this way, for the ground ought to be well cleared and prepared.

Therefore, God scorns this absurd care and diligence in which hypocrites pride themselves, and says that they busy themselves without any benefit. For it is as if a farmer had completely lost his seed, because when the ground is full of briers and thorns, the seed, though it may grow for a time, still cannot bring forth fruit.

For this reason, God commands the Israelites to plough the fallows; as if he were saying that they were like rough ground full of thorns, and that therefore, unusual and by no means common cultivation was needed. For when thorns and briers grow in a field, what benefit will it be to cast seed there? Indeed, a field cannot be well prepared by the plough alone to produce fruit; but much labor is also necessary, as is the case with fallow ground—what is called essarter in our language.

The Prophet, then, implies that the people had become hardened in their vices, and that they were not only full of vices, like a field left uncultivated for two years, but that their vices were so deep that they could not be thoroughly cleared away by ploughing alone, unless they were pulled up by the roots, as they were like thorns and brambles that have been growing in a field for many years.

We see from this that the Prophet refers not only to the impiety, contempt of God, and other sins of the people of Israel, but also to their perverseness. For they had so hardened themselves in their vices for many years that not only the plough was needed, but also other tools to tear up the thorns and eradicate those vices that had formed deep roots.

Therefore, just as he had previously warned them that they would labor in vain unless they returned to God with sincerity of heart and acquiesced in him, so here he commands them to examine their lives, so that they might not cast away their seed like hypocrites who merely make a formal acknowledgment of their sins. Therefore, he commands them to completely shake off their vices, which were hidden within, just as people do who tear up thorns and briers in a field that has long been neglected and left uncultivated.