One aspect of neighbourly love is that we must not merely will our neighbours good, but actually work to bring it about.

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.

A man has free choice to the extent that he is rational.

Beware the man of a single book.

As mariners are guided into port by the shining of a star, so Christians are guided to heaven by Mary.

So, to detract from the perfection of creatures is to detract from the perfection of divine power.

Secondly, man sins against nature when he goes against his generic nature, that is to say, his animal nature. Now, it is evident that, in accord with natural order, the union of the sexes among animals is ordered towards conception. From this it follows that every sexual intercourse that cannot lead to conception is opposed to man's animal nature.