Frederick II of Prussia (1712-1786), later known as the Great, was already referred to by his contemporaries as the "Philosopher of Sanssouci." The king and committed Enlightenment thinker repeatedly engaged critically and commentatively with radical positions, particularly those of the French Enlightenment, since the 1740s. A turning point in his thinking occurred around 1770 when certain representatives of the French radical Enlightenment openly advocated for atheistic and revolutionary positions aimed at the overthrow of European monarchies. Frederick's critique of this, which can be understood as a self-critique of the Enlightenment and as "Enlightenment about the Enlightenment," as well as the famous prize question posed by the Berlin Academy of Sciences regarding the permissibility of "popular deception" in 1780, are addressed in this document.