What did Aristotle warn every one?
Most broadly speaking, things can be classed into categories.
Examples of categories are individual things, actions, and
qualities. (There are other categories too.)
Of course, virtues and vices are qualities of individuals. But
they are not qualities of the body, the physical dimension of a
person. Hairiness and physical strength are qualities of the body.
Virtues and vices are qualities of the soul.
Now we can divide the qualities of the soul into three types:a)
potentialities, like the capacity to feel passions such as fear or
anger or love
b) dispositions or states; these are stable qualities, like
courage or cowardice. (There are states of character, such as moral
virtues and vices; and there are intellectual states, such as
practical wisdom and scientific knowledge.)
c) passions themselves, like fear or anger
Virtues and vices are not passions, though they affect how we
experience the passions. Nor are they mere potentialities, because
these are things we are born with. We are not born virtuous or
vicious.
That means, by elimination, that they must be dispositions or
states.