John Calvin Commentary 1 Corinthians 3:6

"I planted, Apollos watered; but God gave the increase." — 1 Corinthians 3:6 (ASV)

I have planted, Apollos watered. He unfolds more clearly the nature of that ministry by an analogy, in which the nature of the word and the use of preaching are most appropriately depicted. For the earth to bring forth fruit, ploughing, sowing, and other methods of cultivation are needed; but after all this has been carefully done, the farmer’s labor would be of no avail if the Lord from heaven did not give the increase, by the breaking forth of the sun, and still more by His wonderful and secret influence.

Hence, although the farmer's diligence is not in vain, nor is the seed that he throws in useless, yet it is only by God's blessing that they are made to prosper. For what is more wonderful than that the seed, after it has rotted, springs up again!

In like manner, the word of the Lord is seed that is in its own nature fruitful; ministers are, so to speak, farmers who plough and sow. Then follow other aids, such as irrigation. Ministers, too, play a similar role when, after casting the seed into the ground, they assist the earth as much as they can, until it brings forth what it has conceived. But as for making their labor actually productive, that is a miracle of divine grace—not a work of human industry.

Observe, however, in this passage, how necessary the preaching of the word is, and how necessary its continuance is. It would, undoubtedly, be as easy for God to bless the earth without human diligence, so as to make it bring forth fruit on its own, as it is for Him to draw out, or rather press out, its increase at the cost of much human assiduity, sweat, and sorrow. But as the Lord hath so ordained (1 Corinthians 9:14) that people should labor, and that the earth, on its part, should yield a return to their cultivation, let us take care to act accordingly.

Likewise, it would be perfectly in God's power, without human aid, if He so pleased, to produce faith in people while they are asleep. But He has appointed it otherwise, so that faith is produced by hearing (Romans 10:17). The person, then, who, in neglecting this means, expects to attain faith, acts just as if a farmer, throwing aside the plough, taking no care to sow, and abandoning all the labor of farming, were to open their mouth, expecting food to drop into it from heaven.

As to continuance, we see what Paul says here—that it is not enough for the seed to be sown if it is not nurtured from time to time by further help. The one, then, who has already received the seed, still needs watering, nor must efforts cease until full maturity has been attained, or in other words, until life is ended. Apollos, then, who succeeded Paul in the ministry of the word at Corinth, is said to have watered what Paul had sown.