Stephen Hawking and Leonard Mlodinow discussed topics like quantum theory and M-theory, among many others, in an incredibly accessible way. However, I can't give it 5 stars because there were a few passages, particularly towards the end, where I had to re-read a few times to make sense of them and, after finishing the book, I'm left feeling like I learnt so many wonderful things but I can't recall most of them. The narrative thread as we jumped from concept to concept wasn't clear/memorable enough.