My level of scientific understanding and knowledge is, I can now say with confidence, sub-dummy; below dummy; probably, let's be honest, approaching idiot.
This book was written presumably for those with, shall we say, a limited knowledge of physics. That's me. But I like to think I'm intelligent and I did pass A level pure maths (many years ago, I admit. But I'm afraid most of this supposedly simple introduction went way over my head. The last chapter, on Einstein and relativity, was paradoxically the most understandable to my mind and I think I got that. Otherwise - I'm no wiser than when I started.