Right after Louis XVI was guillotined at the Place de la Revolution, at about 10 a.m. on January 21, 1793, Louis XIV's confessor, the Irish-born priest abbe Henri Essex Edgeworth de Firmont, saw one of the executioners – a teenager no older than eighteen – grab the late king's severed head and walk it ceremonially around the scaffold, showing it to the spectators as he let out “the most dreadful cries” (des cris les plus atroces) and made “the most indecent gestures” (des gestes les plus indécents). The teenager did not say a word, let alone present a coherent speech. His expressions of enthusiasm contrasted sharply with the grandiloquence valued by the Immortals of the Academie francaise and violated codes of civility practiced in the Old Regime. But they worked. After a moment of gloomy silence, some spectators exclaimed: “Vive la république!” (Long Live the Republic!) Thousands of spectators joined in, throwing their hats in the air in celebration of the death of Louis XVI.

The execution was much like a scene in a play. The young guard demonstrated his “moral liberty” (la liberté morale), defined in the Encyclopédie as a liberty that “resides in the power that an intelligent being has to do what he wants, according to his own determination” – when he expressed himself by nonverbal cries and gestures. In this instance, his expression of moral liberty had political implications, for he exercised his natural right to express himself, a right articulated in Article 11 of the Déclaration des droits de l’homme et du citoyen de 1789. Here is Keith Michael Baker's 1987 English translation of it: “The free expression [libre communication] of thoughts and opinions is one of the most precious rights of man: thus every citizen may freely speak, write, and print, subject to accountability for abuse of this freedom in the cases determined by law.”

There was nothing special about an executioner getting excited after guillotining a notable criminal in public, but what made Louis XVI's death noteworthy was that the young guard's histrionics were grounded in Enlightenment ideas about the origins of language. Screams exemplified the “cry of nature” (le cri de la nature), defined by Rousseau in the Second Discourse (1755) as “man's first language, the most universal, most energetic, and only language he needed before it was necessary to persuade assembled men.”