Why does the professor mention books and a map? [originaltext] Now listen to

Now listen to part of a lecture in an art class.
    Professor:
    And, you know, still-life’s tool just needs to be straightforward representations. A lot of still-life painters really use the simplicity of the style to send a message or tell a story, even portrays sometimes include elements of still-life paintings. For example, in a portray, there might be a map, hanging on the wall, or there might be some books on the table next to the subject. These objects tell you something about the subject, like maybe that person was well-educated.