Нонфикшн - потому, что это концентрированное знание. Научно-популярные издания помогают понять, что такое человек, что такое мир и что вообще происходит.

You could also try to leave them in the hall of the house you live in. I have lived in many places and have seen English books left not once - they all go in a few days.

Thus spoke Zarathustra - a great book that shows Nietzsche's inner radical nihilism. I haven't red many of his works but i think that's the profound one presenting his honest worldview.