"But since habit is a principle of act, sometimes the name conscience is given to the first natural habit--namely, 'synderesis': thus Jerome calls 'synderesis' conscience (Gloss. Ezech. 1:6); Basil, the 'natural power of judgment,' and Damascene says that it is the 'law of our intellect.'"
— St. Thomas Aquinas (1225-1274)
(I, Q79, A13)