Jakob Bohme (also spelled Jacob Boehme), was a German mystic and theologian who lived during the 16th and 17th centuries. De Signatura Rerum (The Signature of All Things), was written in 1621 and is considered his greatest work. From the preface: "THIS book is a true mystical mirror of the highest wisdom. The best treasure that a man can attain unto in this world is true knowledge; even the knowledge of himself: For man is the great mystery of God,...