Full Idea
You say 'I' and you are proud of this word. But greater than this - although you will not believe in it - is your body and its great intelligence, which does not say 'I' but performs 'I'.
Gist of Idea
Forget the word 'I'; 'I' is performed by the intelligence of your body
Source
Friedrich Nietzsche (Thus Spake Zarathustra [1884], 1.05)
Book Reference
Nietzsche,Friedrich: 'Thus Spake Zarathustra', ed/tr. Hollingdale,R.J. [Penguin 1969], p.62
A Reaction
I'm not sure if I understand this, but I offer it as a candidate for the most profound idea ever articulated about personal identity.