The Signature Of All Things
by Jacob Boehme
If Signatura Rerum by the German mystic Jacob Boehme looks like a book you'd find in the library at a certain school of wizardry, you're not too far off. Boehme discourses at length here on one of the fundamental laws of Magic: the law of signatures, the concept that every object in the real world has some hidden meaning, and particularly how these signatures interact.
At the core of Boehme's philosophy is a mystical Christianity. However, his beliefs were far from that of the Lutheran establishment, and he was persecuted his entire life. Boehme's view of a universe where a creative and destructive principle are in conflict was later repurposed by Hegel as the dialectic. Newton, Nietzsche, the Quaker George Fox, and even Phillip K. Dick have all been cited as being influenced by Boehme.