Piper on worship, emotion and so on.

I just went back to Piper's book Desiring God - Meditations of Christian Hedonist. This is Calvinism in the tradition of Jonathan Edwards, make no mistake. And it is full of purple passages about the emotions or affections that seem to ring true:

Where feelings for God are dead, worship is dead...
True worship must include inward feelings that reflect the worth of God's glory.

These are strong statements - but surely right! Piper says that the right affections give authenticity to the external acts of worship, performed as they are by the will. He turns to the Psalms, especially as they give expression to a genuine brokenness and contrition on the one hand, and to the hearts right desire for God himself on the other.