Writhing in anguish or unfulfilled desire, the figures on The Gates of Hell—more than 180 of them in all—seem to struggle to free themselves from the swirling masses of material behind them. The Gates of Hell began in 1880 when Rodin was commissioned to create a set of portals with bas-reliefs for a proposed Museum of Decorative Arts in Paris. The theme was to be Dante's great poem The Divine Comedy—in particular, its first volume, The Inferno, in which Dante describes a visit to Hell and tells the stories of some of the damned souls he finds there. For artistic inspiration, Rodin drew on Michelangelo's sculpture and on Ghiberti's Gates of Paradise in Florence. Soon, however, Rodin had gone well beyond Dante's poem, incorporating dozens of figures that had no strict parallel in The Inferno. Since the proposed museum was never built, the "gates" never had to be functional, and Rodin was free to change the work again and again over the following decades.

The identifiable borrowings from Dante include the Three Shades, the poet's spirits of the dead, who stand atop the frame and point to the sufferings below. Directly below them sits The Thinker, originally intended to represent Dante himself. About two-thirds of the way down the left door are Count Ugolino and his sons, who endured starvation in a tower until the boys died, at which point Ugolino ate their flesh. Just beneath these figures are the flowing, straining forms of two famous lovers, Paolo and Francesca. Francesca was married to Paolo's elder brother, who ended the adulterous triangle by stabbing the lovers to death. In the right-hand door jamb, at the very bottom, kneels a bearded man thought to be Rodin himself, with a small attendant figure that may represent the fruits of his imagination. At the bottom of each door is a tomb, a reminder of the temporal entrance to Hell.

The gates themselves were never cast in bronze during Rodin's lifetime. When Jules Mastbaum decided to establish the Rodin Museum in Philadelphia, he ordered two bronze casts of the gates, one for his museum and the other for the Musée Rodin in Paris. The first cast came to Philadelphia, where architects Paul Cret and Jacques Gréber incorporated it into the design of the museum's entrance. The Gates of Hell were in place when the Rodin Museum opened to the public in November 1929.

From its origin as a small image of Dante in The Gates of Hell, The Thinker developed into a free-standing sculpture. In 1889 Rodin exhibited a small version that he titled The Thinker, the Poet and identified as a fragment of the gates. But the more he contemplated the image, the more it evolved. By 1902–1904, when he created the enlarged version that is now one of the world's most widely recognized sculptures, the figure had come to represent not Dante in particular but the universal power of creative thought.

The large version of The Thinker was exhibited in Paris in 1904, to so much acclaim that funds were raised to purchase it for the city. This was a time of great social and political turmoil in France, and when the sculpture was installed in front of the Panthéon in 1906, Rodin interpreted it as a "social symbol" magnifying "the fertile thought of those humble people of the soil who are nevertheless producers of powerful energies." In the years thereafter, it may have acquired other meanings for him as well. When his wife died in 1917, he had a cast of The Thinker placed on her grave at Meudon, in front of the ruined façade of an old chateau that Rodin had purchased and installed there. At the same site Rodin himself was buried a few months later.

Philadelphia's Thinker is a cast of the 1902–1904 version. It was installed for the opening of the Rodin Museum in 1929, in front of a façade that replicates the one at Meudon, so that together the sculpture and façade match the arrangement at Rodin's tomb.

Adapted from Public Art in Philadelphia by Penny Balkin Bach (Temple University Press, Philadelphia, 1992).