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"The Four Evangelists stand at the centre of the altarpiece and are pouring the contents of four great bags into a grinder. From the left to right: Mark (with the lion's head), Matthew (in angel form), John (eagle's head) and Luke (bull's head). They are grinding quotes from the Gospels (on the white strips) that refer to man's creation from the Word -- 'In the beginning was the Word.' Symbolically, the apostles' words undergo a transformation -- the four strips become one, and this one strip joins with the figure of the Christ Child in a chalice. the mill, normally used for the manufacture of food, points to the scene's meaning: through the grinding stone the Word becomes flesh, from the grinding stone comes the food of life, and in the grinding stone Christ is sacrificed." -- Edward Norman, The Roman Catholic Church: An Illustrated History
I love that sort of condensing of vision, that ordered conflation; it's something only art does.