“And what more am I? I look for aid to the imagination. [But how mistakenly!] I am not that assemblage of limbs we call the human body; I am not a subtle penetrating air distributed throughout all these members; I am not a wind, a fire, a vapor, a breath or anything at all that I can image. I am supposing all these things to be nothing. Yet I find, while so doing, that I am still assured that I am a something.”

“I think; therefore I am.”

“I doubt, therefore I think, therefore I am.”

“I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake.”

“Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.”

“Cogito ergo sum. (I think, therefore I am.)”

“I am thing that thinks: that is, a things that doubts,affirms, denies, understands a few things, is ignorant of many things, is willing, is unwilling, and also which imagines and has sensory perceptions.”