Verse 18. - Those things. He does not assert that everything which issues from a man's mouth defiles him; for, as was said above on ver. 11, many good things may come from a man's mouth; but he means that the evil to which he gives utterance is fraught with pollution to his moral nature. From the heart. The heart stands for soul, mind, spirit, will, the whole inner man, that which makes him what he is, a conscious, intelligent, responsible being. Hence are attributed to it not only words, but acts, conceptions which issue in external actions, and the consequences which these involve.

15:10-20 Christ shows that the defilement they ought to fear, was not from what entered their mouths as food, but from what came out of their mouths, which showed the wickedness of their hearts. Nothing will last in the soul but the regenerating graces of the Holy Spirit; and nothing should be admitted into the church but what is from above; therefore, whoever is offended by a plain, seasonable declaration of the truth, we should not be troubled at it. The disciples ask to be better taught as to this matter. Where a weak head doubts concerning any word of Christ, an upright heart and a willing mind seek for instruction. It is the heart that is desperately wicked, Jer 17:9, for there is no sin in word or deed, which was not first in the heart. They all come out of the man, and are fruits of that wickedness which is in the heart, and is wrought there. When Christ teaches, he will show men the deceitfulness and wickedness of their own hearts; he will teach them to humble themselves, and to seek to be cleansed in the Fountain opened for sin and uncleanness.But those things which proceed out of the mouth,.... Meaning not material things, as spittle, vomit, &c. but, as it follows, which

come forth from the heart: are first conceived and formed there, and then come forth from thence, and are expressed by the mouth; as all idle words, foolish talking, filthy jesting, unsavoury communication, and every word that is rotten and corrupt, or which is done in the life and conversation;

and they defile the man: the heart is the corrupt fountain from whence all moral defilement flows; and sinful words and actions are the impure streams, which spring from thence, and increase the moral pollution of human nature.