So Ross, incorporating Bywater's transposition of συμβέβηκε τοîς αἰσθητοîς from 24 to 20. Thereby Aristotle distinguishes ‘the three types of objects of perception: the ἲδια αἰσθητά, colour, sound, etc. , the objects to which these belong, but which are here described as being contingent on the ἳδια αἰσθητά , and the κοιυà αἰσθητà, such as movement and size ’—D. Ross, Aristotle De Anima , 6; see also 289.