Origen, "On Prayer"

I've been doing a study of the practice and theology of Christian prayer. Early on I came across a reference to a text by the patristic writer Origen titled simply "On Prayer." The treatise is available in translation for free, courtesy of the good folks at CCEL.org. As part of my ongoing study and reflection on the subject of Christian prayer I will be posting some of my reading notes on this and other texts.
The following notes are from chapters 3-5 of Origen's treatise On Prayer:

chapter 3 is a lengthy argument for the absurdity of prayer in light of God's omniscience and providence, a rhetorical argument against praying that he then responds to in the following chapters. By no means does Origen present a straw man--I am impressed at how honestly he presents this common objection.
This is exactly the difficult question that many believers face at some point: if God already knows everything, and if in his providence he as ordained all things (he uses the example of Jacob and Esau), why bother praying? Origen notes that just as we would think it absurd to pray for sunrise, or for the length of the day to change, it is also seems absurd to pray for God to shorten the time of trial or suffering when we encounter such things.
My own note on this quandary: when one shifts ones focus from the desired effects of prayer and from the action of prayer and focus instead on the believers' attitude and stance before God this argument is deprived of its force. It is no less troubling on a philosophical level—but if what is important about prayer is knowing oneself and knowing God and going through the difficult process of approaching God with a clean heart, these questions fade in significance and urgency.

Chapter 4 is not so much a refutation of the argument contained in chapter 3 as a response. The initial argument is one from free will and runs roughly along the lines of “God has perfect foreknowledge, but his knowledge is not the cause of all future events. God knows before hand what our will is inclined towards and how we will chose, but it is our will that is the cause and not God's foreknowledge.”

In regards to the argument about the sun and the moon, Origen makes the curious yet compelling argument that even the Sun and Moon have free will after a sort, because each praises God in its own way. As the psalmist says “Praise him, Sun and Moon.”
This last point gets again at my observation that prayer is not primarily about getting this or that result, but about the praise, adoration, and presence of God. Just as the sun and moon praise God, so too we praise him through prayer. Indeed, we praise him all the more because we have the gift of self-awareness and so can examine our hearts and minds to ensure we come to him in prayer and praise with a clean heart.