He travelled widely visiting various art collections in his youth, and worked at the Dutch Museum for History and Art before becoming director from 1889 to 1909 of the Mauritshuis. He became a Rembrandt expert who had many differences of opinion with Cornelis Hofstede de Groot. He was a regular contributor to the historical magazines Oud Holland and Künstler-Inventare. In 1922 he left the Netherlands for health reasons and settled in Monaco, publishing books in 1927 on Jan Steen and Rembrandt. He bequeathed his papers to the Rijksbureau voor Kunsthistorische Documentatie, and his art collection lives on in the Museum Bredius. He also bequeathed several Rembrandt paintings to the National Dutch collection.