" While I wanted to think everything false, it must necessarily be that I who thought was something; and remarking that this truth, I think, therefore I am, was so solid and so certain that all the most extravagant suppositions of the sceptics were incapable of upsetting it, I judged that I could receive it without scruple as the first principle of the philosophy that I sought. "

― Bertrand Russell , A History of Western Philosophy