“O God, Thou art my God; early will I seek Thee: my soul thirsteth for Thee, my flesh longeth for Thee in a dry and thirsty land, where no water is; to see Thy power and Thy glory, so as I have seen Thee in the sanctuary.” Psalm 63:1-2 (KJV)
Did the Psalmist know God? David knew God. Yet the more or better he knew Him the more he desired Him.
“Whosoever drinketh of this water shall thirst again: but whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life.” John 4:13-14
The Christian is full of the water that Jesus gives, but is continually in need to drink from the Source. The better we know Jesus the more we desire to know Him.