Paragons of Honesty

Herodotus,  3.72 (tr. Aubrey de Sélincourt)

If a lie is necessary, why not speak it?  We are all after the same
thing, whether we lie or speak the truth:  our own advantage.  Men lie
when they think to profit by deception, and tell the truth for the
same reason – to get something they want, and to be the better trusted
for their honesty.  It is only two different roads to the same goal.
Were there no question of advantage, the honest man would be as likely
to lie as the liar is, and the liar would tell the truth as readily as
the honest man.

George Orwell, Homage to Catalonia (Harvest, 1980), pp. 230-1:

And I hope the account I have given is not too misleading.  I believe that on such an issue as this no one is or can be completely truthful.  It is difficult to be certain about anything except what you have seen with your own eyes, and consciously or unconsciously everyone writes as a partisan.  In case I have not said this somewhere earlier in the book I will say it now: beware of my partisanship, my mistakes of fact and the distortion inevitably caused by my having seen only one corner of events.  And beware of exactly the same things when you read any other book on this period of the Spanish war.