The Eustace Diamonds by Anthony Trollope

When Lord Fawn gave a sudden jump and stalked away towards the house on that Sunday morning before breakfast, Lucy Morris was a very unhappy girl. She had a second time accused Lord Fawn of speaking an untruth. She did not quite understand the usages of the world in the matter; but she did know that the one offence which a gentleman is supposed never to commit is that of speaking an untruth. The offence may be one committed oftener than any other by gentlemen -- as also by all other people; but, nevertheless, it is regarded by the usages of society as being the one thing which a gentleman never does. Of all this Lucy understood something. The word "lie" she knew to be utterly abominable. That Lizzie Eustace was a little liar had been acknowledged between herself and the Fawn girls very often -- but to have told Lady Eustace that any word spoken by her was a lie, would have been a worse crime than the lie itself.

To have brought such an accusation, in that term, against Lord Fawn, would have been to degrade herself forever. Was there any difference between a lie and an untruth? That one must be, and that the other need not be, intentional, she did feel; but she felt also that the less offensive word had come to mean a lie -- the world having been driven so to use it because the world did not dare to talk about lies; and this word, bearing such a meaning in common parlance, she had twice applied to Lord Fawn. And yet, as she was well aware, Lord Fawn had told no lie. He had himself believed every word that he had spoken against Frank Greystock. That he had been guilty of unmanly cruelty in so speaking of her lover in her presence, Lucy still thought, but she should not therefore have accused him of falsehood.