Ver. 16-20. A proper effect discovereth the cause. Lest his disciples should ask, How shall we distinguish true from false teachers? Our Saviour tells them, By their fruits ye shall knowthem. Our Saviour sends not his disciples to inquire into the truth of their mission, whether that more internal from God, of which they could not judge, or more external from men, who may err, and send out those whom God never sent; but you shall know them (saith our Saviour) by their faithful or unfaithful discharge of their duty: if they be true teachers, by their discharging the ministry in a faithful revelation of the mind and will of God, or by their holy life, living as ensamples to the flock; by their fruits of true doctrine and a holy life, by the discharge of their ministry in good conscience; for it is with men as it is with the trees, good trees bring forth good fruit, corrupt trees bring forth evil fruit. If men have the root of the matter; the seed of God abiding in them, they will in every relation bring forth the fruits of truth and holiness: if they have not, they will bring forth error and wickedness. From whence we may learn, that our Lord expecteth from his people such a knowledge of the Scriptures, as that they may be able to discern truth from falsehood; and such a diligence, as to search the Scriptures, whether those things which their teachers deliver to them be according to them or not, Act_17:11; not taking divine truths upon trust, nor believing any thing because dictated by teachers, using their teachers not as dictators, but only as helpers of their faith.