Voltaire 1, Rousseau 0:
As the history of ancient China, Greece and Rome testifies, by bringing people together in the shared enjoyment of the ‘pure pleasures of the mind’ public theatre renders human beings more sociable in their dealings, more moderate in their behaviour, and keener in their judgement. Those nations that are without it cannot be ‘included in the ranks of civilized countries’. Well, at least the pastors of Geneva now knew where they stood. And Rousseau too. ‘Reading your book,’ Voltaire told him, ‘fills one with the desire to walk on all fours.’
Roger Pearson, Voltaire Almighty: A Life in Pursuit of Freedom, p. 248.
The Geneva slur refers to Calvinism, an art-hostile religious doctrine that dominated Geneva during Voltaire and Rousseau’s lifetimes.
Worth noting: Both men were artists at heart. Voltaire first gained fame as a playwright and a poet, and later as a historian and a satirist. Rousseau was a talented musician and composer who later made his name in philosophy.
Strangely, Rousseau was openly hostile to the arts. They are evidence of civilization, a project he largely opposed without any sense of irony.