Boethius identifies beings that are in a subject with what the Scholastics called predicamental accident, and predication by accident with the predication of what is in a subject. The first of these questionable assimilations went on to become terminology commonly accepted by Scholastics of all eras. On the other hand, the second, which seems quite consistent with the thinking of Aristotle, was only admitted with many reservations, probably because of the bewildering claims of Aristotle in Cat. 5, 2a27-34 about the predication of what is in the subject. In what follows I will try to show how these phrases, properly understood, are consistent with the idea that what is in the subject is said by accident of the substance, although they implicate a difficulty poorly resolved by Boethius himself and those who followed him on this point, of whom I will only mention by way of example some Scholastics from the 16th century.