Such things will cease to be written when men perceive that truth is the only merit that gives dignity and worth to history.

John Dalberg, Lord Acton (1834-1902) British historian
“The Massacre of St Bartholomew,” North British Review (Oct 1869)

Referencing Catholic denial and revisionism over the St Bartholomew's Day Massacre. Usually elided to start with "Truth is ..."

Collected in The History of Freedom and Other Essays (1907)