But the movement was interrupted.

And it was interrupted by a man who suddenly stepped out from the ranks of the Encyclopaedists themselves.

Rousseau from his solitary cottage at Montmorency (1758) fulminated the celebrated letter to D'Alembert on Stage Plays.

The article on Geneva in the seventh volume of the Encyclopaedia had not only praised the pastors for their unbelief; it also assailed the time-honoured doctrine of the churches that the theatre is an institution from hell and an invention of devils.
D'Alembert paid a compliment to his patriarch and master at Ferney, as well as shot a bolt at his ecclesiastical foes in Paris, by urging the people of Geneva to shake off irrational prejudices and straightway to set up a playhouse.

Rousseau had long been brooding over certain private grievances of his own against Diderot; the dreary story has been told by me before, and happily need not be repeated.[146] He took the occasion of D'Alembert's mischievous suggestion to his native Geneva, not merely to denounce the drama with all the force and eloquence at his command, but formally to declare the breach between himself and Diderot.