They are embolden with the concept that Truth is not what happened, it is what they say happened. And they happily arrange the facts to accommodate their peculiar way of thinking. Rather than ensuring that their own personal vendetta is presented, they have an obligation to report the event. With heavy emphasis on the word report. This is not to say that they should not offer an opinion, it is that their opinion must be separated from the issues so that it is clearly their mind's offerings.
Translators have the same difficulty in recognizing truth as does the historian.
Both have the obligation to be factual but there is room for interpretation. So it seems to me, at any rate, for whenever he might and should deploy the resources of his pen to praise of so worthy a knight, the author appears to take pains to pass over the matter in silence, all of which in my opinion is ill done and ill conceived, for it should be the duty of historians to be exact, truthful, and dispassionate, and neither interest nor fear nor rancor nor affection should swerve them from the path of truth, whose mother is history, rival of the present, depository of deeds, witness of the past, exemplar and adviser to the present and the future's counselor. On the other hand, since they're so very hostile to us, the author is more likely to have toned down rather than embellished his tale. And here in this account I'm sure you'll find everything you may want, presented in the pleasantest way, and if indeed there's anything worthwhile missing, I'd blame it on its dog of an author, rather than on any deficiency in the subject itself. Part 1, book 2, pp 107.