Observe, 1. It is the wisdom of the wise that they treasure up a stock of useful knowledge, which will be their preservation: Wisdom is therefore found in their lips (Prov. 10:13), because it is laid up in their hearts, out of which store, like the good householder, they bring things new and old. Whatever knowledge may be at any time useful to us we must lay it up, because we know not but some time or other we may have occasion for it. We must continue laying up as long as we live; and be sure to lay it up safely, that it may not be to seek when we want it. 2. It is the folly of fools that they lay up mischief in their hearts, which is ready to them in all they say, and works terror and destruction both to others and to themselves. They love devouring words (Ps. 52:4), and these come uppermost. Their mouth is near destruction, having the sharp arrows of bitter words always at hand to throw about.