Consider first the ratio he gives for the four Galenic degrees of intensity, 1:3:5:8. Where does it come from? The four numbers add up to seventeen. For Jābir, seventeen is the fundamental number for the world—his equivalent, if you will, of what the speed of light or Planck’s constant means for us. He did not pick this number out of a hat. This number recurs throughout the ancient Mediterranean world, beginning with the Pythagoreans, a secretive group founded in the sixth century BC, for whom mathematics was key not only to the material world but to philosophy, religion, and life.
