Full Idea
Why will a man be a two-footed terrestrial animal and not an animal and terrestrial? Assumptions do not make it necessary that what is predicated form a unity - rather, it is as if the same man were musical and literate.
Clarification
'Predicated' means 'having characteristics assigned' to something
Gist of Idea
Why are being terrestrial and a biped combined in the definition of man, but being literate and musical aren't?
Source
Aristotle (Posterior Analytics [c.327 BCE], 92a30)
Book Reference
Aristotle: 'Posterior Analytics (2nd ed)', ed/tr. Barnes,Jonathan [OUP 1993], p.54