PewDiePie mentioned Nicomachean Ethics by Aristotle 3 times

Nicomachean Ethics! Wow what a fun title! Please tell me more Felix! Okay I will! Aristotle the greatest one, no, no, no one of the greatest philosopher of all time. He studied under Plato though he taught Alexander the Great himself. He said all these amazing things thought women had less teeth than men. You could have just checked bro, you had a wife I Googled it. Bro what happened I want to know? Nicomachean Ethics is the first philosopher book that I read that discusses the idea of happiness and 2 300 years or whatever later it is goddamn relevant.

— PewDiePie

On Felix's bookshelf.

In the book Nicomachean ethics by Aristotle, it wasn't actually written by Aristotle it's notes taken down from his lectures [...] some argue this is the most important work of philosophy ever written and in it we get the answer what is virtue according to Aristotle

— PewDiePie