Psalms 36:9

For with thee is the fountain of life - This, in Scripture phrase, may signify a spring of water; for such was called among the Jews living water, to distinguish it from ponds, tanks, and reservoirs, that were supplied by water either received from the clouds, or conducted into them by pipes and streams from other quarters. But there seems to be a higher allusion in the sacred text. ki immecha mekor chaiyim , "For with thee is the vein of lives." Does not this allude to the great aorta, which, receiving the blood from the heart, distributes it by the arteries to every part of the human body, whence it is conducted back to the heart by means of the veins. As the heart, by means of the great aorta, distributes the blood to the remotest parts of the body; so, God, by Christ Jesus, conveys the life-giving streams of his providential goodness to all the worlds and beings he has created, and the influences of his grace and mercy to every soul that has sinned. All spiritual and temporal good comes from Him, the Father, through Him, the Son, to every part of the creation of God.

In thy light shall we see light - No man can illuminate his own soul; all understanding must come from above. Here the metaphor is changed, and God is compared to the sun in the firmament of heaven, that gives light to all the planets and their inhabitants. "God said, Let there be light; and there was light; "by that light the eye of man was enabled to behold the various works of God, and the beauties of creation: so, when God speaks light into the dark heart of man, he not only beholds his own deformity and need of the salvation of God, but he beholds the "light of the glory of God in the face of Jesus Christ;" "God, in Christ, reconciling the world to himself." "In thy light shall we see light." This is literally true, both in a spiritual and philosophical sense.