Teylers Museum was named after Pieter Teyler van der Hulst (1702-1778), a prosperous cloth and silk merchant in Haarlem, and a sponsor of the arts and sciences at the time of the Enlightenment. Inspired by the belief that knowledge was the key to human advancement, Teyler assembled large collections of art and scientific artefacts. Our interview with the American art historian Svetlana Alpers was filmed in the august halls of the Teylers Museum library. Ms Alpers talks about the unique visual culture of the 17th century and the importance that artists and scientists attached to observation.