Matthew 13:47 - Ellicott's Commentary On The Whole Bible

The kingdom of heaven is like unto a net. — The net in this case is not the hand-net of Matthew 4:18, but the sagenè, or great drag-net, which drew in a larger haul of fishes. The day’s teaching in the method of parables ends, as it were, in an easy lesson, which the former experience of the disciples would enable them to understand. Still, as in the parable of the Tares, the main thoughts are, (1) the mingling of the evil with the good in the visible kingdom of Christ on earth, and (2) the ultimate separation of the two, that each may receive according to the divine law of retribution. Here, as there, the parable perforce passes over the fact that in the actual work of the kingdom the very casting of the net may change, and is meant to change, the nature of the fish that are taken in its meshes, and, therefore, that those that remain “bad” are so in the end by the result of their own will.