In this artwork, how is the abstract discussed?
The Captive Slave is a painting by British artist John Simpson, which was first exhibited in London in 1827. The portrait shows a man, manacled, on a stone bench and looking pensively or plaintively upward.  Its subject matter, historical period, and mode of creation suggest the artist intended the painting as an abolitionist statement. 
After being displayed again in 1828, the painting was not given another public showing for 180 years, until it was purchased by the Art Institute of Chicago in 2008.
abolitionist Art Institute of Chicago John Simpson portrait London