parsha bit: Vayikra
The book of Vayikra describes in detail the various korbanot
(sacrifices) to be brought under different conditions. After the
destruction of the temple this was no longer possible, and the rabbis
declared prayer to be a temporary replacement. The Rambam held that
this was not meant to be temporary; it was part of the progression from
animal sacrifice to prayer to intellectual contemplation. In modern
times, Rabbi Abraham Joshua Heschel said that prayer doesn't replace
sacrifice; it is sacrifice. We sacrifice selfishness and greed
in a quest for truth, mercy, and love. (Man's Quest for God: Studies
in Prayer and Symbolism, as cited in another torah commentary not
presently to hand.)