The Thinker (Le Penseur) is probably the artist's most famous work—and certainly also his most parodied work.
Actually, Rodin's Thinker was originally made for a specific topic. He is contemplating Hell. Originally part of Rodin's larger sculpted scene entitled The Gates of Hell, the statue has since been singled out, separated from its context, and taken today to merely represent a generalized symbol of philosophy. But Rodin originally intended the work to focus on this specific issue, and an added element of proof for that lies in the figure's nudity. The Thinker is nude in reference back to the Renaissance works of Michelangelo to hearken back to the more religious subject matter of artwork from that time period. The nudity of this sculpture and Rodin's other sculptures also hearkens back to Classical traditions of Hellenistic pathos. The Impressionistic edge to works such as this is to be found in the emotional impact they are meant to have on the viewer. When we see this man in deep thought we are meant to likewise be inspired to think about the problem of Hell. In that sense, Rodin conveys the idea of his subject matter almost more than he sculpts an actual figure. The nude man could be anybody; it doesn't matter. What matters is the latent subject of what he is mulling over in his head, and we get a feel for (or an impression of) the profundity of his thoughts by looking at the seriousness of his facial expression, the tension within his muscular body, and his weighty pose as he rests upon a formless slab of stone. His head seems to rest heavy on his knuckles because his thoughts rest heavy on his mind and on his heart. It's fun to parody The Thinker, and I certainly enjoy a good laugh; but at the end of the day, when considering its subject, the subject of Hell, this work of art sits heavy on my mind as well. We ought all to fall sober at the contemplation of Hell—I know I do.