 Cleanthes points out that if philosophy asserts the distinction between common life and science, philosophy would set itself against some of the best supported parts of natural philosophy which are often most removed from common life. We may naturally think that the Sun is in motion, but the reality behind the appearances can be very surprising. Cleanthes’s point is that philosophy cannot hope to argue against the authority of science without looking as backward as monks and inquisitors (who attacked Copernicanism).