 Van Eeden's psychiatrist practice included treating his fellow Tachtiger Willem Kloos as a patient starting in 1888.His treatment of Kloos was of limited benefit, as Kloos deteriorated into alcoholism and increasing symptoms of mental illness.Van Eeden also incorporated his psychiatric insights into his later writings, such as in a deeply psychological novel called "Van de koele meren des doods" (translated in English as "The Deeps of Deliverance").