A cartoon showing an artist creating a self portrait.
The self portrait sculpture looks exactly like the artist.
The cartoon is partly about the self-obsession of (some) artists and about the introspection of artists and the self-referential nature of art.
Part of the joke in the cartoon is that not only is the sculptor carving a statue, but the the sculpture (the self portrait) is also working on a self portrait too (that is just protruding into the right hand side of the cartoon).
It is a cartoon about infinite regression, where the artist is creating a self portrait that is creating a self portrait… and so on.