Try the authors Robin Hobb, Christopher Paolini, Cornelia Funk, Terry Pratchett, George Orwell, Hermann Hesse (Specifically Siddhartha), Sun Tzu (Art of War) and Karl Marx. The first 4 are all modern Authors of fantasy/fiction. George Orwell an early 20th century author who wrote the iconic books Animal Farm and 1984. Hermann Hesse was born in 1877 and died in 1962, he wrote mostly philosophical books, one of which I personally think changed the way I think; Siddhartha. He also wrote the book The Glass Bead Game, which I'd suggest reading after Siddhartha to get use to the genre. Sun Tzu is a 400bc writer (he is pretty old), wrote pretty much a military scripture about war strategies which is still used today. Karl Marx is another philosophical author and wrote about the at the time 'theory' of Communism. I'd highly recommend finding some stuff from that, something will interest you.