He (Mohammed) seduced the people by promises of carnal pleasure to which the concupiscence of the flesh urges us. His teaching also contained precepts that were in conformity with his promises, and he gave free rein to carnal pleasure. In all this, as is not unexpected; he was obeyed by carnal men. As for proofs of the truth of his doctrine, he brought forward only such as could be grasped by the natural ability of anyone with a very modest wisdom. Indeed, the truths that he taught he mingled with many fables and with doctrines of the greatest falsity.
Thomas AquinasTo restore man, who had been laid low by sin, to the heights of divine glory, the Word of the eternal Father, though containing all things within His immensity, willed to become small. This He did not by putting aside His greatness but by taking to Himself our littleness.
Thomas AquinasIt would seem that the ingratitude, whereby a subsequent sin causes the return of sins previously forgiven, is a special sin. For, the giving of thanks belongs to counter passion, which is a necessary condition of justice. But justice is a special virtue. Therefore this ingratitude is a special sin. Thanksgiving is a special virtue. But ingratitude is opposed to thanksgiving. Therefore ingratitude is a special sin.
Thomas AquinasHe suddenly announced that he could not write any more since "All that I have written seems like straw to me."
Thomas AquinasIt is altogether unlawful to kill oneself... Wherefore suicide is contrary to the inclination of nature, and to charity whereby every man should love himself... Life is God's gift to man, and is subject to His power, Who kills and makes to live. Hence whoever takes his own life, sins against God... for it belongs to God alone to pronounce sentence of death and life.
Thomas Aquinas