Among a very select few others including the Bible and the Code of Hammurabi, this is one of the most important books ever written. This is where Isaac Newton first publicly put forth the calculus and the scientific method. A tremendous intellectual rupture that we are still dealing with, this book was indirectly responsible for historical shifts such as the Enlightenment and the Industrial Revolution. No mean feat.<br><br>The Principa is not an introductory calculus for the modern reader. It is written in Newton's own notational style. This style is different from the modern one, used in calculus today. The modern calculus notation system was devised by Leibniz. Newton's system of notation proved less useful than Leibniz's, and the better one has won out. Leibniz had independently discovered the calculus prior to the publication of Principia. Thus, Leibniz was not influenced by Newton's notational style. Leibniz's discovery of the calculus was made in secret on the continent several years after Newton had made his own secret discovery of it in Britain. Leibniz's work was published only after Newton's Principia was published. This led Newton to wrongly believe that his work had been stolen. An epic debate between the British and Continental academies ensued with each side championing their man.<br><br>This book has enormous historical interest. For a person who is already educated in calculus, this book will take you to the source of the subject matter, the mouth of the Nile, so to speak. As for the scientific method, this is where it was conceived.