Thomas Aquinas, on 1Thess 5:21

“But prove all things; hold fast that which is good.”

“Then he says, but test everything, he shows how they ought to behave towards everything; and one piece of advice is that they should make use of discretion in all matters. "Your spiritual worship" (Rom. 12:1). In this matter there should be a careful examination, the election of the good, and the rejection of the evil. In treating the first point Paul says, do not despise prophesying, nevertheless, test everything, that is, those which are dubious; for matters that are evident do not require examination. "Do not believe every spirit" (1 Jn. 4:1). "Does not the ear try words?" (Job 12:11). Concerning the second, he says, hold fast what is good. "For a good purpose it is always good to be made much of" (Gal. 4:18).”

Imported from an open dataset — not yet checked against the printed edition.