/summa/SS/SSIII/SS_Q130:
We must now consider the vices opposed to magnanimity; and in the first place, those that are opposed thereto by excess. These are three, namely, presumption, ambition, and vainglory. Secondly, we shall consider pusillanimity which is opposed to it by way of deficiency. Under the first head there are two points of inquiry:
(1) Whether presumption is a sin?
(2) Whether it is opposed to magnanimity by excess?