I've seen bad reviews for master works of science in the past. Mostly they claim these books are either not clear or impossible to understand. Don't buy this book for the purpose of learning Classical Mechanics or Calculus from it, but for the scientific curiosity of learning how the great Isaac Newton presented his revolutionary scientific ideas to the world. Of course, it is difficult to read. This is a translation of a book written in Latin more than 300 years ago!<br>This book is a jewel. Just like the original works of Einstein, Maxwell, Heisenberg, Schroedinger and all those giants. Many of the ideas presented in the book were written for the first time in history and probably they are not organized in a didactic form. The person buying this book should not expect to find a clear textbook when originally it was not written for the layman, but for the expert scientific community of its time. Buy this book, sit back, scan through it, and enjoy a true piece of history.