"I think, therefore I am" - or, for Latin speakers, “Cogito, Ergo Sum”. With these words, René Descartes gave philosophy its most epic mic drop. In a world full of uncertainties, Descartes found the one thing he couldn’t doubt: his own existence.

Descartes, a French philosopher, mathematician, and all-around smarty-pants, was searching for an undeniable truth in an age of scepticism. When he reached this famous conclusion, he published it in French as “je pense, donc je suis” in his 1637 Discourse on the Method, so as to reach a wider audience than Latin would have allowed.

Even if an all-powerful demon were tricking him into thinking that he exists when he does not, he would still have to exist in order for the demon to deceive him. Descartes 1 - Demon - 0.