Several inspirations influenced Rodin's creation of The Thinker. The foremost is the work of Dante Alighieri, the poet whom the figure was originally supposed to represent Dante wrote his epic poem The Divine Comedy between 1308 and 1321. The popularity of this poem at the end of the 19th century could well have been the reason Rodin chose this subject as the theme of his sculpture The Thinker.
A trip to Italy in 1875 further opened Rodin's eyes to the achievement of the past: Michelangelo, Donatello, and Ghiberti. He later noted that Michelangelo saved him from academicism. To Rodin, there was something poetic about the heroic nude and that type of heresy and romanticism was what he wanted to capture in his sculpture. Stylistically the sculpture The Thinker resembles the heroes of Michelangelo and the nude young men whom Rodin felt best to represent in a romantic and creative light.
Hugo Rheinhold was a contemporary of Rodin and a German Impressionist sculptor. He produced and exhibited sculpture Affe mit Schadel (Ape with Skull) before The Thinker was created and this work may well have influenced Rodin. What inspired Rheinhold in making his sculpture is unknown, although it has obvious parallels with Auguste Rodin's The Thinker. Both artists shared an appreciation of natural, realistic compositions. Affe mit Schadel shows the ape in the position of Auguste Rodin's Thinker while seated upon a pile of books.