William IV, Landgrave (or count) of Hesse-Kassel from 1567, is called “the Wise” because of his accomplishments in political economy and the natural sciences.

The partition of the Hessian lands at that time had left William with little basis for a forceful foreign policy.

Domestically, he has sought a compromise between Lutherans and Calvinists.

He is an outstanding organizer and a skilled economist.

The Ökonomische Staat (1585), a territorial survey compiled for him, is a model of administrative statistics.

William also pursues scientific studies and perhaps owes his lasting fame to his research in astronomy.

On friendly terms with the great Danish astronomer Tycho Brahe, he constructs numerous astronomical instruments and calculates many stellar positions.