"Je pense, donc je suis" -- Descarte
So said he; "I think, therefore I am"
I can see how he would get to that conclusion, with a being based on thought.
I disagree with him, though, as I see thought as an extended expression of feelings. Going back to basics, going back to origins, thoughts seem to start with a feeling, an intuition, an emotion.
I feel, therefore I am.
Je sens, donc je suis.