Not so - The word translated "so" is taken by some in its etymological force as "strong," "firm," and the passage is rendered "the heart of the fool disperseth (supplied from the first clause) what is weak and unsteady," i. e., "falsehood and unwisdom." The Septuagint takes it as an adjective, "the heart of the fool is unstedfast." The phrase as it stands in the King James Version is, however, of frequent occurrence Genesis 48:18; Exodus 10:11; Numbers 12:7.

The lips of the wise disperse knowledge,.... Scatter it about for the benefit of others; they are communicative and diffusive of it unto others, that fruit may abound to their account: so the first ministers of the Gospel diffused the savour of the knowledge of Christ and his Gospel in every place; their words went into all the earth, and their sound to the end of the world; and so every Gospel minister will speak according to the oracles of God, and according to the abilities and measure of the gift which he has received; and to the utmost of his power feeds souls with knowledge and understanding;
but the heart of the foolish doth not so; does not disperse knowledge, for he has no solid substantial knowledge in him: or, "the heart of the foolish is not right" (x); it is full of folly and wickedness: or "the heart of the foolish does not disperse that which is right" (y); true and right things, and the knowledge of them; but, on the contrary, as in Proverbs 15:2, "pours out foolishness".
(x) "non erit rectum", Pagninus, Baynus; "non est rectum", Piscator, Mercerus. (y) "Spargit quod abest a recto", Junius & Tremellius, Amama; "eventilant non rectum", Schultens, Cocceius.

We use knowledge aright when we disperse it; but the heart of the foolish has nothing to disperse that is good.

(Compare Proverbs 10:20-21).
heart . . . not so--not right, or vain.

A second series which begins with a proverb of the power of human speech, and closes with proverbs of the advantages and disadvantages of wealth.

7 The lips of the wise spread knowledge;
But the direction is wanting to the heart of fools.
It is impossible that לא־כן can be a second object. accus. dependent on יזרוּ (dispergunt, not יצּרוּ, Proverbs 20:28; φυλάσσουσι, as Symmachus translates): but the heart of fools is unrighteous (error or falsehood) (Hitzig after Isaiah 16:6); for then why were the lips of the wise and the heart of the fools mentioned? לא־כן also does not mean οὐχ οὕτως (an old Greek anonymous translation, Jerome, Targ., Venet., Luther): the heart of the fool is quite different from the heart of the wise man, which spreads abroad knowledge (Zckler), for it is not heart and heart, but lip and heart, that are placed opposite to each other. Better the lxx οὐκ ἀσφαλεῖς, and yet better the Syr. lo kinı̂n (not right, sure). We have seen, at Proverbs 11:19, that כן as a participial adj. means standing = being, continuing, or also standing erect = right, i.e., rightly directed, or having the right direction; כּן־צדקה means there conducting oneself rightly, and thus genuine rectitude. What, after 7a, is more appropriate than to say of the heart of the fool, that it wants the receptivity for knowledge which the lips of the wise scatter abroad? The heart of the fool is not right, it has not the right direction, is crooked and perverse, has no mind for wisdom; and that which proceeds from the wise, therefore, finds with him neither estimation nor acceptance.

Disperse - Freely communicate to others what they know.