In the eighteenth century, dissimulation was no longer a means for
defending free thinkers from the dangers of censorship, but it primarily became
an instrument of self-censorship. Dissimulation responded to the desire not to
divulge potentially subversive truths to the populace. The essay reflects on the
use of the mechanisms of concealment by the French heterodox thought. The

philosophes – although theorists of the fight against prejudices and against religious imposture – in the political sphere considered it legitimate to keep hidden

certain truths, harmful at a social and economic level. This duplicity between
the speculative level and the practical level of the Enlightenment reflection can
be correctly understood by studying a metaphor attributed to Fontenelle. It is
the image of the hand full of truth to be prudently kept closed in front of the
people. This metaphor is cited and reinterpreted by all the leading exponents
of the French Enlightenment: d’Alembert, Voltaire, Helvétius and d’Holbach.
Fontenelle, as heir of the seventeenth century erudite libertinism and forerunner
of the Enlightenment, allows us to reread the desire to disseminate knowledge,

typically attributed to the philosophes, in the light of the conservatism and elitism that emerges in their works.