Don't you say, 'There are yet four months until the harvest?' Behold, I tell you, lift up your eyes, and look at the fields, that they are white for harvest already.
The comparison of converted souls to a harvest made a profound impression upon John who made five references to it in as many verses  (Revelation 14:14-19). "Send forth thy sickle and reap; for the hour to reap is come; for the harvest of the earth is ripe," etc.