Full Idea
We should not say "It thinks" in preference to "I think". If thinking is an active, voluntary process, there must be a self who thinks.
Gist of Idea
Thinking must involve a self, not just an "it"
Source
John Searle (Rationality in Action [2001], Ch.3.IX)
Book Reference
Searle,John R.: 'Rationality in Action' [MIT 2001], p.94