What principles did Goya use when he painted Carlos IV of Spain? and how? and where?
http://www.google.com/search?q=goya+painting+carlos+iv&oq=goya+painting+carlos+iv&aqs=chrome..69i57j0l2.14967j0j7&sourceid=chrome&espv=210&es_sm=122&ie=UTF-8
Read, read, read, read ... and let us know what you discover.