This is a free online ebook, and what a great resource it is. Norton's explanations are lucid and engaging at every turn. All the material here feels comprehensible if one is just willing to sit and think it over for a little. Then suddenly Norton is dealing with the most wide-ranging questions surrounding philosophy/physics/science, and making you feel as if you can actually engage with arguments surrounding the topic. I am very curious to read more about places other physicists/philosophers would disagree with him, because he makes all of his own views on the matter seem so reasonable. By no means do I actually think I understood most of the material with that much depth (much more math would be required for that), but as an introduction to these issues this is near perfect.