10 But, passing over in the mean while the depth of knowledge, to deal with you as I think I ought to deal with my intimate friend; that is, as I have myself power, not as I have wondered at the power of very learned men; there are three kinds of error, whereby men err, when they read anything. I will speak of them one by one. The first kind is, wherein that which is false is thought true, whereas the writer thought otherwise. A second kind, although not so extensive, yet not less hurtful, when that, which is false, is thought true, yet the thought is the same as that of the writer.
A third kind, when from the writing of another some truth is understood, whereas the writer understood it not. In which kind there is no little profit, rather, if you consider carefully, the whole entire fruit of reading. An instance of the first kind is, as if any one, for example, should say and believe that Rhadamanthus hears and judges the causes of the dead in the realms below, because he has so read in the strain of Maro. For this one errs in two ways: both in that he believes a thing not to be believed, and also in that he, whom he reads, is not to be thought to have believed it.
The second kind may be thus noticed: if one, because Lucretius writes that the soul is formed of atoms, and that after death it is dissolved into the same atoms and perishes, were to think this to be true and what he ought to believe. For this one also is not less wretched, if, in a matter of so great moment, he has persuaded himself of that which is false, as certain; although Lucretius, by whose books he has been deceived, held this opinion. For what does it profit this one to be assured of the meaning of the author, whereas he has chosen him to himself not so as through him to escape error, but so as with him to err.
An instance suited to the third kind is, if one, after having read in the books of Epicurus some place wherein he praises continence, were to assert that he had made the chief good to consist in virtue, and that therefore he is not to be blamed. For how is this man injured by the error of Epicurus, what though Epicurus believe that bodily pleasure is the chief good of man: whereas he has not surrendered up himself to so base and hurtful an opinion, and is pleased with Epicurus for no other reason, than that he thinks him not to have held sentiments which ought not to be holden.
This error is not only natural to man, but often also most worthy of a man. For what, if word were brought to me, concerning some one whom I loved, that, when now he was of bearded age, he had said, in the hearing of many, that he was so pleased with boyhood and childhood, as even to swear that he wished to live after the same fashion, and that that was so proved to me, as that I should be shameless to deny it: I should not, should I, seem worthy of blame, if I thought that, in saying this, he wished to show, that he was pleased with the innocence, and with the temper of mind alien from those desires in which the race of man is wrapped up, and from this circumstance should love him yet more and more, than I used to love him before; although perhaps he had been foolish enough to love in the age of children a certain freedom in play and food, and an idle ease?
For suppose that he had died after this report had reached me, and that I had been unable to make any inquiry of him, so as for him to open his meaning; would there be any one so shameless as to be angry with me, for praising the man's purpose and wish, through those very words which I had heard? What, that even a just judge of matters would not hesitate perhaps to praise my sentiment and wish, in that both I was pleased with innocence, and, as man of man, in a matter of doubt, preferred to think well, when it was in my power also to think ill?
Source: On the Profit of Believing (New Advent)