Some malicious demon of the utmost power and cunning has employed all his energies in order to deceive me. I shall think that the sky, the air, the earth, colours, shapes, sounds and all external things are merely the delusions of dreams which he has devised to ensnare my judgement ... I have convinced myself that there is absolutely nothing in the world. Does it now follow that I too do not exist? No: If I convinced myself of something then I certainly existed ... let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something.

Reconstruct this, in your words, as an argument in the standard (premises-conclusion) form.