[The words] of St. Justin, philosopher and martyr, from the fifth part of his Apology: — I reckon prosperity, O men, to consist in nothing else than in living according to truth. But we do not live properly, or according to truth, unless we understand the nature of things.
It escapes them apparently, that he who has by a true faith come forth from error to the truth, has truly known himself, not, as they say, as being in a state of frenzy, but as free from the unstable and (as to every variety of error) changeable corruption, by the simple and ever identical truth.— From the writings of John of Damascus.
Source: Miscellaneous Fragments from Lost Writings (New Advent)