Arnold Tholinx, a well-known physician in Amsterdam, was a brother-in-law of Jan Six, a friend of Rembrandt’s. That is perhaps how the artist came to be commissioned to make this portrait. It is executed with a confident, yet meticulous hand as an etching with drypoint, and it emphasizes Tholinx’s scholarship: he is seated at a table, looking up from his books, still holding his reading glasses.