Anslo was born in Amsterdam as the fourth son of the Norwegian born Dutch cloth merchant Claes Claesz. Anslo (from Oslo).^[1] His older brothers Claes, Jan, and Reyer all became syndics of the drapeniers guild. His brother Reyer's son Reynier or Reyer became a poet.^[1] Cornelis married Aeltje Gerritsdr. Schouten in 1611 and was called 14 July 1617 to the Mennonite group in Amsterdam known as the Waterlanders.^[1] The poet Joost van den Vondel was deacon of his church and wrote a poem in his honor, mentioning Rembrandt, who portrayed him several times in drawings and etchings.^[1] Vondel wrote a wedding poem for Anslo's son Gerbrand Cornelisz. Anslo when he became engaged to Abigel Schouten on 20 March 1636.^[2] Vondel also wrote a wedding poem for Anslo's granddaughter Alida on 28 September 1658.^[3] Alida married Michael Blok, the brother of Agnes Block, Vondel's niece with whom he spent much of his time in his later years.

Anslo's father founded a hofje in Amsterdam that the Anslo brothers managed during their lifetime. The hofje was partially demolished and rebuilt on the original location, today's Eglantierstaat 52. Anslo became a pamphleteer during the 1625-1628 Amsterdam Mennonite conflict between Nittert Obbes, Hans de Ries and others and published an anonymous pamphlet as an attempt to prevent a schism.

Anslo died in Amsterdam.

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  Portrait of Anslo and his wife, by Rembrandt.
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  Anslo hofje

• Anslo, Cornelis Claesz (1592-1646) on GAMEO