...since man should act according to reason, he is truly a slave when he is led away from what is reasonable by something alien. Furthermore, if he is not restrained by the yoke of reason from following concupiscence, he is free only in the opinion of those who suppose that the highest good is to follow one's concupiscence.
St. Thomas Aquinas, Commentary on the Letter of St. Paul to the Romans, The Aquinas Institute for the Study of Sacred Doctrine (Lander, WY: 2012) p. 174]
