Herschel recounts a story about Voltaire and makes arrangements to visit De Morgan.

He quotes from Sir Isaac Newton (‘Tho’ often he forgot to Eat / Never forgot to drink Sir!’), noting that this: ‘is a noble illustration but it puts me in mind of Voltaire’s rather unscrupulous procedure in re Habakkuk. On the chance of your not knowing it (rather a slender one since you seem to be use to, if not the actual author of all the fun that is going on in the world) I will tell it. He, the said Voltaire, was dictating a “moral” essay (after his fashion) to his secretary & was going on at a great rate quoting Habakkuk[…] The poor secretary wrote all down but with increasing dismay & misgiving till at length his heart kindled & he spoke with his tongue “Mais, Monsieur, Habakkuk ne dit nul part rien de parcil!!” Voltaire was down upon him at once with “Taissez vous, insolent! S’il ne le dit pas il l’a pu dire. Habakkuk est capable de tout!” Isn’t that sublime?’

The certificate states that Voltaire follows and observes social and religious laws at the Château de Ferney.