Context: Jesus, after delivering the Sermon on the Mount, healing the afflicted, and choosing and instructing his twelve disciples, continues His travels about the country. When He condemns the towns of Galilee for not repenting their sins, He begins to arouse the Pharisees. He defends His disciples' plucking corn on the Sabbath and His healing of a man's withered hand on the Sabbath as blameless. Accused of casting out a devil in the name of Beelzebub, He argues that Satan would not logically war against his own kind, states the fact of two opposing forces, and compares the passive man with a scatterer of flocks. Further, He asserts that each force or tree will produce according to its own kind.
Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit.