J.-A. Dassier, Portrait of Charles de Secondat, Baron de Montesquieu (Public Domain)
Montesquieu’s De L’Esprit de Lois or Spirit of the Law from 1748 contains an argument for free speech and a seperation of words from actions:
“Words do not constitute an overt act; they remain only in idea … Since there can be nothing so equivocal and ambiguous as all this, how is it possible to convert it into a crime of high treason? Wherever this law is established, there is an end not only of liberty, but even of its very shadow …”
– Montesquieu, De L’Espirit de Lois (1748) bk. 12 ch. 12-13
Montesquieu has a tremendous influence on the founding fathers.