Almost by definition, philosophical issues are at a high level...C1, at least. Paulo Coelho ( you can read in English translation) Gives you a lot to think about in any of his books. The Little Prince is simple language (originally in Frence: le petit Prince) but available in translation., and excellent. To Kill a Mockingbird/Harper Lee is lwritten about the American South, including racist issues, and is an excellent coming o f age story. Enjoy!