John Chrysostom — as excerpted in the Catena Aurea on Matthew 13:36-43

“For this is part of the wiles of the Devil, to be ever mixing up truth with error. The harvest is the end of the world. In another place He says, speaking of the Samaritans, Lift up your eyes, and consider the fields that they are already white for the harvest; (John 4:35.) and again, The harvest truly is great, but the labourers are few, (Luke 10:2.) in which words He speaks of the harvest as being already present. How then does He here speak of it as something yet to come? Because He has used the figure of the harvest in two significations as He says there that it is one that soweth, and another that reapeth; but here it is the same who both sows and reaps; indeed there He brings forward the Prophets, not to distinguish them from Himself, but from the Apostles, for Christ Himself by His Prophets sowed among the Jews and Samaritans. The figure of harvest is thus applied to two different things. Speaking of first conviction and turning to the faith, He calls that the harvest, as that in which the whole is accomplished; but when He enquires into the fruits ensuing upon the hearing the word of God, then He calls the end of the world the harvest, as here.”