Proverbs 15:2, 4, 7 The tongue of the wise uses knowledge aright: but the mouth of fools pours out foolishness. A wholesome tongue is a tree of life: but perverseness therein is a breach in the spirit. The lips of the wise disperse knowledge: but the heart of the foolish does not so. 

‘The tongue of the wise uses knowledge aright: but the mouth of fools pours out foolishness.’ A wise man uses knowledge rightly, but a fool has no true sense of its proper use.

‘A wholesome tongue.’ A gentle tongue speaks truth and life, but a piercing tongue kills the soul.

‘Tree of life’ [Hebrew: ‛ets; chayiy], tree of lives, because it produces constant and eternal life (15:4; 3:18; 11:30; 13:12; Gen. 2:9; 3:24; Rev. 2:7; 22:2, 14). In these passages, a literal tree of life is meant.

Sixteen sources of Life: The tree of Life (15:4; 3:18; 11:30; 13:12; Gen. 2:9; 3:24; Rev. 2:7; 22:2, 14). The path of life (Ps. 16:11; Pro. 5:6). The fountain of life (Ps. 36:9; Pro. 13:14; 14:27; Rev. 7:17). The well of life (10:11; John 4:14). The way of life (10:17; 15:24). The wellspring of life (16:22). The bread of life (John 6:35). The ways of life (Acts 2:28). The Prince of Life (Acts 3:15). The Spirit of life (Rom. 8:2; Rev. 11:1-19). The savour of life (2Cor. 2:16). The Word of Life (Php. 2:16; 1Jn. 1:1-10). The promise of life (2Tim. 1:1). The hope of life (Tit. 3:7). The grace of life (1Pet. 3:7). The water of life (Rev. 22:1; 17).

Four figurative Trees of Life: Wisdom and understanding (3:18), the fruit of the righteous (11:30), hope and desire fulfilled (13:12), and a wholesome tongue (15:4).

‘The lips of the wise.’ It is in the heart of the wise to spread knowledge, but not so with fools.