Refers to the actual material substances used to make a work of
art

No, i don't believe that a portrait has the same weight as it did a long time ago. i don't believe if the president were to send a portrait of himself to an ally it would reaffirm a relationship. portraits have lost a lot of there meaning now and it is quite sad. in today's society if you want to create or strength a relationship you wouldn't send them a portrait you would send them money or other gifts of value. in today's society authority would be based on power that the person has. most powerful people try and keep them selfs from looking weak so others won't doubt them, so if a man of authority were to send someone a portrait to reaffirm a relationship i believe it would make them look weak. those with authority use there power telling others what they are to do.

Aa i believe is the answer to your question