[2] Adriaan Koerbagh and his younger brother Johannes (1634–72) were sons of a ceramics maker, who died young leaving them funds allowing them to pursue extended schooling.
[3][4] He was one of the most radical figures of the Age of Enlightenment, rejecting and reviling the church and state as unreliable institutions and exposing theologians' and lawyers' language as vague and opaque tools to blind the people in order to maintain their own power.
Koerbagh put the authority of reason above that of dogmas and was thus seen as a true freethinker, although twentieth century notions of him as an anarchist or libertarian cannot be applied with certainty.
He wrote in books 't Nieuw Woorden-Boeck der Regten (The New Dictionary of Rights, 1664), and in Een Bloemhof van allerley lieflijkheyd (A Flower Garden of All Sorts of Delights, 1668), under the pseudonym Vreederijk Waarmond.
The Church authorities were offended by the dictionary's articles on religious and political topics, forcing Koerbagh to flee to Culemborg, a legally autonomous town in another province that would not extradite him, and then to Leiden.