Aphorisms by Nietzsche
Nietzsche's Beyond Good and Evil is a book of aphorisms with universal and timeless relevance. It is a classic text whose ideas remain contemporary and are discussed in many contexts.
Beyond Good and Evil and the German original Jenseits von Gut und Böse are both available for free download at Gutenberg.org. They are only in text format so they need to be converted before they can be read on a palm.