The Lord knoweth. God searches the heart. The particular thing which it is here said that he knows, is, that the thoughts of man are vain. They have this quality; and this is that which the psalmist here says that God sees. The affirmation is not one respecting the omniscience of God, but with respect to what God sees of the nature of the thoughts of the wise.

The thoughts of the wise. Their plans, purposes, designs.

That they are vain. That they lack real wisdom; they are foolish; they shall not be accomplished as they expect, or be seen to have that wisdom which they now suppose they possess.

{b} "again" Ps 94:11