Who was Isaac Newton? In his own age, Newton was a god of reason who created a perfect and perfectly rational universe. To a later and more romantic age, he became a monster, a bizarre unsociable creature who stripped the world of its rich mystery. More recently he has been outed as a closeted mystic who delved deeply into religious prophecy and alchemy. As John Maynard Keynes famously pronounced, “Newton was not the first of the age of reason. He was the last of the magicians.” Which Newton do you see? James Gleick does a fine job in this book of telling the story not only of the man, but of how he was perceived. After all, where exactly are the lines that separate magic, religion, and science? They are foggy enough even now, and in the 17th century they were indiscernible. Newton, in pursuing occult matters, wasn’t engaged in a childish sideshow. He was doing the same thing that led him to his law of universal gravitation. He could not know that his investigations into the biblical prophecies of Daniel would not lead him to results as fundamental as his physics. He was simply doing what he did better than anyone before or since: observing, theorizing, experimenting, and systematizing. In so doing he sharpened the lines between what we now think of as the clear and separate domains of science, magic, and religion, though this was certainly not his intent. It’s just that his science succeeded where his theology did not. But who can blame him for thinking that his vision could penetrate any topic? Gleick’s book is very good, a sympathetic and rounded portrait of a strange and extraordinary man.