Many thanks to Carl Kinbar, who e-mailed me with the source of the Abraham Joshua Heschel quote which I referenced in my last post:
"Prayer is meaningless unless it is subversive, unless it seeks to overthrow and to ruin the pyramids of callousness, hatred, opportunism, falsehoods.... The liturgical movement must become a revolutionary movement, seeking to overthrow the forces that continue to destroy the promise, the hope, the vision. We pray because the disproportion of human misery and human compassion is so enormous." (From "On Prayer," in Moral Grandeur and Spiritual Audacity, ed. Susannah Heschel, Farrar Straus Giroux 1996, pp 262-263.)
Thanks, Carl, for the citation. I've added the book to my Amazon wishlist, and look forward to reading it soon, to see the quote in its context.