Speech is too often not, as the Frenchman defined it, the art of concealing Thought; but of quite stifling and suspending Thought, so that there is none to conceal.

Thomas Carlyle
Thomas Carlyle (1795-1881) Scottish essayist and historian
Sartor Resartus, Book 3, ch. 3 (1834)
    (Source)

Referring to Talleyrand. Quoting Herr Teufelsdröckh.

This passage first appeared in Fraser's Magazine for Town and Country, Vol. 9, No. 54 (1834-06).