The document discusses how letter writing became increasingly popular in 17th century Dutch art. Artists like Gerard ter Borch, Gabriel Metsu, Pieter de Hooch and Johannes Vermeer featured images of people writing, dictating, receiving, sending and reading letters. At this time, letters were seen as a way to convey private feelings between individuals rather than just business matters. The introduction of letter pairs showing both the sender and receiver underscored the intimacy of letter correspondence.