From which, regarding the testimony of his country as more trustworthy than Timaeus's spite, I pronounce with confidence that the life of Demochares was guiltless of all such offences.
And even if, as a fact, Demochares had the misfortune to be guilty of any such thing, what circumstance or what event compelled Timaeus to record it in his history?
For just as men of sense when they meditate revenge on their enemies do not examine in the first place what others deserve to suffer, but rather how it becomes themselves to act, so when we bring reproaches we must not in the first place consider what is fitting for our enemies to hear, but regard it as of the greatest importance to determine what is proper for ourselves to speak.
In the case, therefore, of writers who measure everything by the standard of their own passions and jealousies, we must suspect all their statements and refuse credit to them when extravagant.
So that in the present case I may claim to be justified in rejecting the slanders of Timaeus concerning Demochares,
whereas this author can claim neither pardon nor credit from anyone, as he has in his reproaches so obviously let himself be carried beyond the bounds of decency by the spitefulness which was engrained in him.
Walbank Commentary