Epitasis and Anesis in Aristotle, De caelo 2.6

Abstract

De caelo 2.6 describes irregular motion differently from the discussion at Physics 5.4. The desire to make the one discussion congrue with the other has strained interpretation of the De caelo passage. Aristotle provides a theory of irregular motion that is tripartite and the passage ought to be interpreted in such a way as to explain this tripartite motion. Akmē is not a ‘top speed’ as it is generally translated, but a point in an object’s motion when epitasis must become anesis. Although the terms epitasis and anesis cover ‘acceleration’ and ‘deceleration’ they cannot be reduced to them.