William Shakespeare posited the famous To be or not to be - I guess Being and Time is actually less philosophical than that, but perhaps more artistic somehow. Is Being and Time a real book? - Heidegger also asked “What is thinking?“ - obviously, also in the same vein as To be or not to be; after all, I think therefore I am. - That's what Descartes said. But time, that's the real mystery, the secret: we don't know if time really exists.