Here's something to ponder - has his pose changed?

Did Rodin's famous "The Thinker" sculpture always have his open hand on his chin, or was it a closed fist on his forehead?

There are many people who remember him with the closed first on his forehead. As a test, next time you talk to someone unaware of this Mass Memory Discrepancy Effect ask them to make the famous Thinker pose - chances are, they'll do the fist-forehead one. 

Few people realise there were many copies of the sculpture, the most famous being Le Penseur in the Musée Rodin in Paris. Begun in 1880, The Thinker was initially a figure in a large commission for a doorway surround called The Gates of Hell, and Rodin based this on Dante's Divine Comedy.

Representing philosophy, one can only wonder what he'd make of all the controversy surrounding his pose over a century after his creation...

Origin

Rodin was commissioned to create a doorway surround in 1880, and called the first version of the statue, which was part of this set The Poet. The whole set was called The Gates of Hell, and was themed on Dante's Divine Comedy. The thinking statue was larger than the others and directly over the door, so some took it as representing Dante himself. Rodin wanted the sculptures to evoke the same feelings of majestic human anatomy as Michelangelo. About 28 casts were made and are in various locations around the world. Some have been made since his death, but are not considered canon. One was placed in the Hotel Biron in Paris, which Rodin was using to store some of his sculptures. He worked to made the building a formal museum named after him, which was opened in 1919.

Changed to more than 2 poses

There are even reports there are more than 2 poses, as described here