He really sits as the famous sculpture.
The Thinker (Le Penseur in French) is a bronze sculpture on marble pedestal by Auguste Rodin, whose first cast, of 1902, is now in the Musée Rodin in Paris; there are about 28 original castings, as well as various other versions, studies, and posthumous castings.
It depicts a man in sober meditation battling with a powerful internal struggle. It is often used to represent philosophy.