The first Jesuits left Pont-à-Mousson on 16 October 1603, and reached La Flèche on 2 January 1604. They started to teach grammar,rhetorics, Latin, Greek, Hebrew, philosophy, mathematics, and theology. A foundation edict was issued at Fontainebleau in May 1607, in which the building started to take its present shape.
René Descartes was one of the first and most famous students of the school from 1607 to 1615, and introduced the school in his Discourse on Method under the phrase “I was in one of the most famous schools of Europe”.
The College continued to expand, and, upon the death of Henry IV, a vast church was built, in which the hearts of Henry IV and his wife queen Marie de Medicis were enshrined.