[the thinker]

For a good book written for teens/young adults and that is easier to read than some of the older texts, I'd suggest any book by Stephen Law. I started out with Philosophy Rocks! and it gives a pretty good overview of some philosophical ideas, including Plato's the cave and the question can you jump in the same river twice? It shows both sides pretty well and then leaves you to decide for yourself what you think. I've probably read it three or four times, and it's really good to get you thinking.