As an instance of Voltaire's convictions, Hall wrote in The Friends of Voltaire, "I disagree of what you say, but I will defend to the death your right to utter it." This phrase, which is often credited to Voltaire, is frequently used to express the notion of free speech. It is found in many a legal oath and has been adopted as a motto by groups as diverse as the United States Marine Corps and the Hitler Youth. Voltaire himself used it in a letter to the Archbishop of Paris when he was being tried for writing "God does not exist". He had written "I disagree with what you say, but I will defend to the death your right to utter it". In fact, this exact quotation from Hall's book appears on the front page of his trial transcript. In addition to this letter, there are two other instances where he used this phrase in his writings. The first time was in 1763 during the controversy over the publication of John Wilkes' attack on Lord Bute. At that time, people were threatening violence if Wilkes' articles weren't banned. So, to protect Wilkes' right to free speech, Voltaire wrote "I disagree with what you say, but I will defend to the death your right to utter it". The second time was in 1775 after the outbreak of the American Revolution.