Cogito ergo sum

Cogito ergo sum means, "I think, therefore I am." It comes from a famous phrase written by a philosopher named René Descartes. When Descartes was younger, he doubted the existence of everything and said he would believe something only if he could prove it. Eventually, he realized he could be certain of one thing—that he must exist if he is thinking. He concluded that thinking is the only thing he could be certain was real, and Cogito ergo sum was born! Basically, it is a way of saying that if you are able to think, you must exist, and it is a reminder that you can always trust yourself and your thoughts.