Do not wish to jump immediately from the streams to the sea, because one has to go through easier things to the more difficult.

Man can sin against nature in two ways. First, when he sins against his specific rational nature, acting contrary to reason. In this sense, we can say that every sin is a sin against man's nature, because it is against man's right reason.

For it is necessary in every practical science to proceed in a composite (i.e. deductive) manner. On the contrary in speculative science, it is necessary to proceed in an analytical manner by breaking down the complex into elementary principles.

There can be no joy in living without joy in work.

Good and evil are essential differences of the act of the will. For good and evil pertain essentially to the will; just as truth and falsehood pertain to the reason, the act of which is distinguished essentially by the difference of truth and falsehood (according as we say that an opinion is true or false.) Consequently, good and evil volition are acts differing in species.

Three conditions are necessary for Penance: contrition, which is sorrow for sin, together with a purpose of amendment; confession of sins without any omission; and satisfaction by means of good works.

The Study of philosophy is not that we may know what men have thought, but what the truth of things is.