Adam Clarke on 1 Corinthians 3:6

I have planted - I first sowed the seed of the Gospel at Corinth, and in the region of Achaia.

Apollos watered - Apollos came after me, and, by his preachings and exhortations, watered the seed which I had sowed; but God gave the increase. The seed has taken root, has sprung up, and borne much fruit; but this was by the especial blessing of God. As in the natural so in the spiritual world; it is by the especial blessing of God that the grain which is sown in the ground brings forth thirty, sixty, or a hundred fold: it is neither the sower nor the waterer that produces this strange and inexplicable multiplication; it is God alone. So it is by the particular agency of the Spirit of God that even good seed, sown in good ground, the purest doctrine conveyed to the honest heart, produces the salvation of the soul.