William Gilbert wrote the influential book De Magnete.
The concepts influenced Boyle and Newton, who saw in it some deeper alchemical substances , fluid in nature, but too occult to discuss openly. In fact it was that substance that Gilbert called Electra that so intrigued them, for it seemed to be curiously at odds with Lodestone magnetism and the magnetism of iron, It created a spark which was audible, attracted a different class of substances and mage animals jump. For that reason it was called animal magnetism. Thus it was considered to e some form of magnetism.
Distinction between electricity and magnetism. An amber stick when rubbed affects a rotating needle made of any type of metal (a versorium) and attracts paper, leaves and even water. But electricity is different to heat and to magnetism which only attracts iron-bearing materials (he calls it coition). He shows the effects of cutting a spherical loadstone (which he calls a terrella) through the poles and equator and the direction of attraction at different points. Magnets act at a distance but the force has no permanent presence and is not hindered like light. Materials including gold, silver and diamonds are not affected by magnets, nor can one produce perpetual motion.
On animals and magnetism in organisms
This work of Dr Gilbert's relates chiefly to the loadstone, and what we call magnets; that is, pieces of steel which have acquired properties similar to those of the loadstone. But he extends the term magnetism and the epithet magnetic, to all bodies which are affected by loadstones and magnets, in a manner similar to that in which they affect each other. In the course of his investigations, indeed, he finds that these bodies are only such as contain iron in some state or other; and in proving this limitation he mentions a great variety of phenomena which have a considerable resemblance to those which he allows to be magnetical, namely, those which he called electrical, because they were produced in the same way that amber is made to attract and repel light bodies. He marks, with care, the distinctions between these and the characteristic phenomena of magnets. He seems to have known, that all bodies may be made electrical, while ferruginous substances alone can be made magnetical.
p.xvii (quoting John Robison)
on the measurement of electricity
Amongst the many other ingenious contrivances frequently alluded to in his book, Gilbert mentions the versorium, an iron needle moving freely upon a point, with which he was enabled to measure excited electricity. He is besides the inventor of "two most ingenious and necessarie Instruments for Sea men to find out thereby the latitude of any place upon sea or land, in the darkest night, that is without the helpe of Sunne, Moone or Starre." These instruments are described in Thomas Blunderville's quarto work entitled "The Theoriques of the seven Planets, shewing their diverse motions… printed at London 1602."
This NASA sponsored website provides additional information but all histories of the influence of magnetism on electricity leave out Arago's fundamental observation on the effect of rotation on "diamagnetic or non magnetic" materials/
The experimentation of Gilbert on electrification affecting all kinds of materials including metals , and the coupling with a magnetic "versorium" is not understood to this day. Eddy currents are the usual explanation, but the connection with "magnetic rotation" is misconstrued.
http://physics.info/magnetism/ tries to coerce a view consistent with electricity being cause.
In the 1770s Austrian physician Franz Mesmer arrived in Paris with a radical theory of animal magnetism, based on Hermetic philosophy, that the human microcosm corresponds to world macrocosm. Mesmer said the body has magnetic poles, and a subtle fluid flows from cosmic magnetic poles through the body. Uninterrupted, smooth flow is health; blockages create disease. Mesmer claimed to remove blocks and restore flow by stroking the body with magnets. Inexplicably, his treatments worked. Mesmer became famous — and rich — until a French medical commission declared him a fraud. Mesmerism is still derided by science, but association with trance induction is metaphoric.
In contrast, animal electricity prospered at this time in experiments by Italian scientists Galvani and Volta of electric effects on living tissue. But it was to be in the next century that the world would make a giant leap into the vortex.
The connection to light and plasma was intuited , because it is everywhere. The manifestation of electricity involved with magnetism is a an unravelled mystery, because rotation is left out of the explanation.
Hermes wandered in a rocky, desolate place to meditate and pray. Following secret instructions of the Temple, he freed his higher consciousness from bondage to his physical senses. Thus released, his divine nature revealed to him The Mysteries. He beheld a terrible, awe-inspiring figure: the Great Dragon, with wings stretching across the sky and light streaming in all directions from its body.
The Great Dragon called Hermes by name, and asked why he meditated on the World Mystery. Terrified, Hermes prostrated himself before the Dragon, beseeching it to reveal its identity. The great creature replied it was Poimandres, the Mind of the Universe, Creative Intelligence, and Absolute Emperor of all.
Hermes besought Poimandres to disclose the nature of the universe and the constitution of the gods. The Dragon acquiesced, bidding Hermes hold its image in his mind. Immediately Poimandres' form changed. Where it had stood was a glorious, pulsating Radiant LightP the spiritual nature of the Great Dragon itself. Hermes was "raised" into the midst of this Divine Effulgence and the material universe faded from his consciousness…..
from The Vision of Hermes Trismegistus
a fragment of ancient Hermetic science