Saint Thomas Aquinas

He who is dying of hunger must be fed rather than taught.

...the goodness of the will depends on the intention of the end.

Not everything that is more difficult is more meritorious.

Beware the man of one book.

Three things are necessary for the salvation of man: to know what he ought to believe; to know what he ought to desire; and to know what he ought to do.

Perfection of moral virtue does not wholly take away the passions, but regulates them.