Felix Klein was born in Düsseldorf, the son of an official. He ended high school in Düsseldorf, also he studied physics at the University of Bonn. Initially, he planned to become a physicist. At this time, Julius Plücker was head of the Department of Mathematics and Experimental Physics in Bonn, and Klein became his assistant. However, Plücker's main interest was geometry. Under his leadership, Klein became a physician in 1868.