An interesting bit of theology

I was reading in Psalm 37 this morning, and found an interesting phrase in verse 11:

but the meek shall inherit the earth

Yes, we 've read that somewhere else, haven't we? In fact, most of the Beatitudes have a link to something said in the Psalms. And so I wonder why Christ appears to have quoted the Psalms a lot--despite our day's tendency to treat them as "only poetry," it seems that He felt there was a lot of theological meat to them.

Apart from the obvious fact that they are also God's inspired Word, He also doesn't say much about why He quotes them so often. Is it a subtle rebuke to the Sadducees, who didn't recognize the canonicity of anything but the Torah? Is it a rebuke to the Pharisees, who claimed (wrongly) to know the Law, but did not have the heart of God, as David did?

Is it a way of bringing in the heart of God to the discussion among those not of the Pharisees or Sadducees? A way of communicating that the entirety of the Tanach is indeed God's Word? A way of communicating the unity of God's Word, as Pslams are quoted next to Torah, history, and Prophets? A hint for Protestants to come 15 centuries later as to the best way to worship in song?

Or perhaps, a bit of all the above. Whatever He was thinking when He quoted Psalm 37:11 in the Beatitudes, we could do little better, I think, than to read and meditate on a Psalm today.