O Lord, how great are thy works! - Compare Psalms 8:3; Psalms 40:5. See also the notes at Job 11:7. The meaning here is this: The psalmist, on the Sabbath, in giving himself to meditation on the works of God, is overwhelmed with a sense of their vastness, their incomprehensible nature, and the depth of wisdom evinced, far beyond the grasp of man, in what God had done. How soon is man lost; how soon does he get beyond his depth; how soon does he feel that here is greatness which he cannot comprehend, and wisdom which he cannot fathom, and goodness which he cannot appreciate, when he sits down to meditate on the works of God!
And thy thoughts are very deep - Compare Isaiah 28:29; Romans 11:33-34. The meaning is, that the plans or the purposes of God, as evinced in the works of creation and providence, are too profound for man to understand them. Who but God himself can comprehend them?