Man, above all other substances, and above all other living things, was perpetually acting upon his fellows by means of this invisible effluence.
Star vibrates light to star, may soul to soul
Strike through some finer element of her own.
This natural action and reaction could, the alchemists taught, be strengthened in particular cases by the exercise of will-power, by the practice of medicine, and by magical arts. "By the magic power of the will," Paracelsus writes, "a person on this side of the ocean may make a person on the other side hear what is said on this side. . . the ethereal body of a man may know what another man thinks at a distance of 100 miles and more." A later mystic, the Scottish physician Maxwell asserts that physician who has learnt to influence his patient's vital spirits can cure that patient's disease at any distance by invoking the aid of the universal spirit.
This conception of an influence which emanates from all things in the universe, but from human bodies in particular, was popularised by that genius among quacks, Franz Antoine Mesmer. Many of Mesmer's followers in France, Germany, and England proved, or thought they proved, that there did indeed radiate such an invisible healing effluence from the mesmerist to his patient. The proof was chiefly exhibited in the power of the mesmerist—or hypnotiser as we should now call him—to send his subject into the trance or to
