The Herborn Academy (Academia Nassauensis) was a Calvinist-Reformed institution of higher learning in Herborn from 1584 to 1817. The Academy was a centre of encyclopaedic Ramism and the birthplace of both covenant theology and pansophism. Its faculty of theology continues as the Theological Seminary of the Evangelical Church of Hesse and Nassau.
In 1584 Count John VI of Nassau-Dillenburg founded the Academia Nassauensis as a post-secondary institution. He established it upon the request of his brother William the Silent, Prince of Orange in the year of the latter's death. The sovereign granted the students two warm meals and three liters of small beer per day. The Academy (Paedagogium) was originally located in the Herborn Castle. In 1588 Johann purchased the old town hall and, after expanding it, gave it over for the Academy’s use. This academy, which later took on a distinctively Calvinist cast, was further augmented with four faculties much like a conventional university. It quickly became one of the most important educational locations of the Calvinist-Reformed movement in Europe, becoming well-known as a centre of encyclopaedic Ramism and as the birthplace of covenant theology and pansophism.
Despite repeated efforts and the undisputed quality of the teaching, Herborn Academy was never given the imperial authorization to designate itself a university, largely because it was a Calvinist foundation. As a result, the school never possessed the authority to grant doctorates.
During the period 1594 to 1599/1600 and 1606 to 1609, the Academy moved from Herborn to Siegen, where it was accommodated in the buildings of the lower castle.