Aristotle was a very smart chap, but it's hardly the case that everything he said was unchangeable truth. (Random examples: his fundamental physics was really, really wrong -- see http://csep10.phys.utk.edu/astr161/lect/history/aristotle_dy... for a very brief summary of some important errors; he said that men and women have different numbers of teeth, which they don't; his distinction between "substance" and "accidents" has been pretty much abandoned for ages, with the possible exception of the Roman Catholic Church's teaching on transubstantiation.)