Full Idea
If men needed speech in order to learn to think, they had a still greater need for knowing how to think in order to discover the art of speaking.
Gist of Idea
Language may aid thinking, but powerful thought was needed to produce language
Source
Jean-Jacques Rousseau (Discourse on the Origin of Inequality [1754], Part I)
Book Reference
Rousseau,Jean-Jacques: 'The Basic Political Writings', ed/tr. Cress,Donald A. [Hackett 1987], p.49
A Reaction
I take language to be a consequence of the emergence of meta-thought in humanity, so I thoroughly endorse Rousseau's view. The idea that rationality, and even consciousness, are mainly facilitated by language strikes me as quite wrong.