“Already I had learned from thee that because a thing is eloquently expressed it should not be taken to be as necessarily true; nor because it is uttered with stammering lips should it be supposed false. Nor, again, is it necessarily true because rudely uttered, nor untrue because the language is brilliant.”
V, 6
Variation on the middle sentence: A thing is not necessarily true because badly uttered, nor false because spoken magnificently.
Variation on the middle sentence: A thing is not necessarily false because it is badly expressed, nor true because it is expressed magnificently.
Confessions (c. 397)
Context: Already I had learned from thee that because a thing is eloquently expressed it should not be taken to be as necessarily true; nor because it is uttered with stammering lips should it be supposed false. Nor, again, is it necessarily true because rudely uttered, nor untrue because the language is brilliant. Wisdom and folly both are like meats that are wholesome and unwholesome, and courtly or simple words are like town-made or rustic vessels — both kinds of food may be served in either kind of dish.
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Aurelius Augustinus 183
early Christian theologian and philosopher 354–430Related quotes

“A thing is not necessarily true because a man dies for it.”
The Portrait of Mr. W. H. http://www.planetmonk.com/wilde/portrait/wh01.html (1889)

“It should be said that such an art would be neither more false nor more true than classical art.”
Cubism was born

“We can never add more truth to what is true already, nor make that true which is false.”
p, 125
The History of Oracles, and the Cheats of the Pagan Priests (1688)

The Earthly Paradise (1868-70), The Lady of the Land
Context: What man art thou that thus hast wandered here,
And found this lonely chamber where I dwell?
Beware, beware! for I have many a spell;
If greed of power and gold have led thee on,
Not lightly shall this untold wealth be won.
But if thou com'st here knowing of my tale,
In hope to bear away my body fair,
Stout must thine heart be, nor shall that avail
If thou a wicked soul in thee dost bear;
So once again I bid thee to beware,
Because no base man things like this may see,
And live thereafter long and happily.

Pope Urban VIII on Private Revelation http://www.medjugorje.org/purban.htm (2001).
Whether or not Urban VIII said this is debated. He did make a public statement about private revelations and their dissemination in the Catholic Church in his Constitution, Sanctissimus Dominus Noster of 1625-03-13.
Misattributed quotes