Augustine of Hippo, on Titus 1:15

“All things are clean to the clean: but to them that are defiled, and to unbelievers, nothing is clean: but both their mind and their conscience are defiled.”

“But now, when you abstain for the sake of chastising the body from various kinds of food that are in themselves quite permissible, remember that "to the pure all things are pure"; don't regard anything as impure except what unbelief has defiled; "for to the impure and unbelievers," the apostle says, nothing is pure. But naturally, when the faithful are reducing their bodies to slavery, whatever is deducted from bodily pleasure is credited to spiritual health.”

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