  In 1889 Rickert moved to Freiburg for health-related reasons. Rickert’s health was always precarious. After undergoing intestinal surgery in 1896 he suffered lifelong intercostal neuralgia and he developed agoraphobia. In spite of his health problems, Rickert was able to complete his Habilitation under Alois Riehl (1844–1924) in Freiburg, where he was appointed extraordinary professor in 1894 and ordinary professor in 1896. The dissertation he produced for the Habilitation, The Object of Knowledge, is one of his most important works and a milestone in early twentieth century Neo-Kantianism.