"When Sir Isaac was working on the Principia, " said Daniel, "I paid him a visit up at Trinity. He had requested what seemed to me to be an odd lot of information: tables of the tides, data on a certain comet, astronomical observations of Jupiter and Saturn. Well, it was a long ride, and by the time I had reached Cambridge I’d managed to work out that there was a common thread running through all of these: gravity. Gravity causes the tides and determines the orbits of comets and planets alike. To us it is obvious now; but back then it was by no means agreed that a comet, let us say, might be bound by the same force that kept the Earth in its gyre. Isaac’s triumph was to perceive that all of these phænomena were attributable to the same cause, working everywhere in the same way. Now, I have long been nonplussed by Isaac’s Alchemical research, but as years have gone by I have perceived that he would achieve a similar triumph by finding a single common underlying explanation for phænomena that we think of as diverse, and unrelated: free will, God’s presence in the Universe, miracles, and the transmutation of chymical elements. Couched in the willfully obscure jargon of the Alchemists, this cause, or principle, or whatever one wants to call it, is known as the Philosopher’s Stone, or other terms such as the Philosophic Mercury, the Vital Agent, the Latent or Subtile Spirit, the Secret Fire, the Material Soul of Matter, the Invisible Inhabitant, the Body of Light, the Seed, the Seminal Virtue."