Commentators explain that this verse highlights a key principle of God's work: it's a collaborative effort across generations. The Old Testament prophets and John the Baptist "sowed" the seed by preparing people for the Messiah. Jesus's disciples were now "reaping" the harvest of that labor. This encourages believers to value both the sowers who faithfully plant seeds and the reapers who gather the harvest, as both roles are essential and share in the final joy.