Matthew 12:35 - Ellicott's Commentary On The Whole Bible

A good man out of the good treasure. — A whole parable is wrapt up in this last word. Every thought and desire of a man is added to the ever accumulating store of such desires or thoughts in the inner chamber of his heart, and thence passes out into word or deed. In the ideal division of the context, which excludes neutrality, the treasure is either simply good or simply evil. Practically, it might seem as if the character of most men implied a treasure of good and evil mingled in ever-varying proportion, but that thought is traversed in its turn by the fact that if there is not the unity of goodness which comes from the love of God, there must be the distraction and diversity that come from the love of self, and that this makes the treasure predominantly evil. The poison of worldliness acts in such a case with accumulative power. The same image reappears in reference to the intellectual side of the religious life in Matthew 13:52.