Charles H. Spurgeon on Psalms 139:8

Thou art there. This is not meant of his knowledge, for that the Psalmist had spoken of before: Ps 139:2-3, "Thou understandest my thought afar off: thou art acquainted with all my ways." Besides, "thou art there"; not thy wisdom or knowledge, but thou, thy essence, not only thy virtue. For having before spoken of his omniscience, he proves that such knowledge could not be in God unless he were present in his essence in all places, so as to be excluded from none. He fills the depths of hell, the extension of the earth, and the heights of the heavens. When the Scripture mentions the power of God only, it expresses it by hand or arm; but when it mentions the spirit of God, and doth not intend the third person of the Trinity, it signifies the nature and essence of God; and so here, when he saith, "Whither shall I go from thy spirit?" he adds exegetically, "whither shall I flee from thy presence?" or Hebrew, "face"; and the face of God in Scripture signifies the essence of God: Ex 33:20,23, "Thou canst not see my face", and "my face shall not be seen"; the effects of his power, wisdom, providence, are seen, which are his back parts, but not his face. The effects of his power and wisdom are seen in the world, but his essence is invisible, and this the Psalmist elegantly expresses. —Stephen Charnook.