Around the web, you will find the following:
Cornelius Tacitus: He had a certain frankness and generosity, qualities indeed which turn to a mans ruin, unless tempered with discretion.
The thought was striking, as indeed it should strike anyone who is fairly open, like myself. But is it Tacitus?
Well it is! It is in fact from the Histories, book 3, chapter 86, as translated by A.J.Church and W.J.Brodribb (London, 1873 in this case, p.140.) It is a description of the character of Vitellius!