He encontrado en Wikiquote a la responsable, Evelyn Beatrice Hall, ella lo escribió, (por lo visto)
I did not mean to imply that Voltaire used these words verbatim and should be surprised if they are found in any of his works. They are rather a paraphrase of Voltaire's words in the
Essay on Tolerance — "Think for yourselves and let others enjoy the privilege to do so too."
En cualquier caso, yo también comparto la opinión.
