Psalm 36:9, “With you is the fountain of life; In your light do we see light,” is a strange line. I looked it up in three books: a modern commentary, a summary of medieval Christian commentaries, and the medieval midrash on the Psalms.
A modern critical commentary: Peter C. Craigie, in volume 19 of the Word Biblical Commentary (Psalms 1-50), helpfully recommends viewing “thy light” as shorthand for “the light of thy countenance,” as in Psalm 4:7 and more importantly Numbers 6:25-6: “The Lord make his face shine upon you.” So “we will be enlightened by the light of your face.” That helps make the passage a bit less dense.
A summary of medieval commentators: Thomas de Vilanova (1488-1555) says, “Scarcely anywhere else in the whole Psalter do we so find the Son and the Holy Ghost, and the Sacraments, preached as here. It is as if David spoke with John’s voice… with Paul’s voice.” John Mason Neale (1818-1866) thinks this verse, understood as referring to the Son coming from the Father, is the source of the phrase “light of light” in the Nicene Creed (381). And Thomas Aquinas hangs detailed argumentation about the mode of the beatific vision on this verse. In Neale’s summary: “In order to see the Essence of God, some kind of similitude to that Essence on the part of the visual power is requisite; in opposition to those who taught, as later and poorer theologians have endeavoured to prove, that the Vision itself is habitual to beatified spirits.”
Wherefore, sings Gerhoch of Reichersberg (1093-1169):
Glory be to the Father, with Whom is the Well of Life, and to the Son, in Whose light we shall see light; and to the Holy Ghost, Whose righteousness standeth like the strong mountains. As it was in the beginning, is now, and ever shall be, world without end.
Midrash Tehillim (Medieval Jewish commentary embodying older traditions): So good I quote it in full:
R. Johanan said: It happened that a man lighted a lamp which went out, and each time he lighted it, it went out, until at last the man said, ‘How long shall I keep tiring myself with this lamp? I will wait for the shining of the sun and go about in its light.’
Similarly, when the children of Israel were enslaved in Egypt, Moses rose up and redeemed them, but they were enslaved again in Babylon. Then Daniel, Hananiah, Mishael, and Azariah rose up and redeemed them, but they were enslaved again in Elam, in Media, and in Persia. Then Mordecai and Esther rose up and redeemed them, but they were enslaved again in Greece. Then the Hasmonean and his sons rose up and redeemed them, but they were enslaved again in Edom the wicked. Thereupon the children of Israel said: ‘We have grown weary of being enslaved and redeemed, only to be enslaved once again. Now let us pray not for redemption through flesh and blood, but through our redeemer, the Lord of hosts whose name is the Holy One of Israel. Now let us pray not that flesh and blood give us light, but that the Holy One, blessed be He, give us light, as is said For with thee is the fountain of life; in thy light we shall see light, and also The Lord is God, and He will give us light (Ps. 118:27)”
R. Johanan’s (d. 279?) insight here is striking: By contrasting this constant light, the true light, with a series of good but impermanent lights, he underlines the personalism that is so central to the spiritual vision of the Psalms. The Lord himself must do the redeeming, or the redemption will fade into the past, be overcome by ever-renewed slavery, and require renewal itself. No redemption carried out through agents or mediators is sufficient; redemption must come through the one who is inherently, in himself, the Redeemer.
“We have grown weary of being enslaved and redeemed, only to be enslaved once again. Now let us pray not for redemption through flesh and blood, but through our redeemer, the Lord of hosts whose name is the Holy One of Israel.”
Amen and amen!