Although largely neglected in the literature, Benjamin Constant was one of Rousseau's most powerful and subtle nineteenth-century critics. In the first part of this essay, I have revived Constant's criticism of Rousseau's conception of freedom and tyranny. In the second part, I have provided counterfactual evidence in an attempt to show how Rousseau would have responded to Constant's interpretation. By demonstrating both Constant's criticism and Rousseau's defense, I have depicted the relationship between these two thinkers as a dialogue — a dialogue on the meaning of freedom and tyranny.