Full Idea
I think it is likely that we are the only creatures that can think about the contents of our thoughts.
Gist of Idea
We are probably the only creatures that can think about our own thoughts
Source
Jerry A. Fodor (The Elm and the Expert [1993], §4)
Book Reference
Fodor,Jerry A.: 'The Elm and the Expert' [MIT 1995], p.92
A Reaction
I think this is a major idea. If you ask me the traditional question - what is the essential difference between us and other animals? - this is my answer (not language, or reason). We are the metathinkers.