In the beginnings, Protestant theology was very hostile to all kinds of metaphysics. Theology and Aristotelian philosophy excluded themselves each other. During the later 16th and the early 17th century the attitude towards philosophy and even metaphysics changed. It appeared impossible to teach theology without discussing metaphysical questions. Thus Aristotelian metaphysics returned to the protestant universities and colleges. At the little university of Duisburg Johannes Clauberg, under the influence of Nederland cartesianism and covenant theology, started an new philosophical approach to theology which fitted in very well with the tolerant church regiment of prince of this region, the duke Elector of Brandenburg.