W. James King

“ But more important than his scientific speculations, is the insight he can give us into a Renaissance philosophy of nature and its relation to medieval thought. One does not find in De magnete a prototype of modern physical science in the same sense one can in the writings of Galileo and Kepler. Instead one finds here a full-fledged example of an earlier kind of science, and this is Gilbert's main value to the historian today. ”

“ Gilbert's De magnete was not the first attempt to determine the nature of the loadstone and to explain how it could influence other loadstones or iron. It is typical of Greek philosophy that one of the first references we have to the loadstone is not to its properties but to the problem of how to explain these properties. Aristotle [11] preserved the solution of the first of the Ionian physiologists: "Thales too ... seems to suppose that the soul is in a sense the cause of movement, since he says that a stone has a soul because it causes movement to iron." ”

“ One no longer had a central reference point for absolute space; there was no "motor essentialis" focused upon the earth but one had only the mutual motion of the heavenly bodies. The natural distinction between heaven and earth was gone, for the earth was no longer an inert recipient but a source of wonder, and so the stage was set for the universe of Giordano Bruno. [213] The Aristotelian philosophy of nature was used to justify a new cosmology, but there was no break with the past such as one finds in Galileo and Kepler. ”

“ In this manner is obtained the natural downward motion of earth and the natural upward motion of fire.
Local motion can also be caused by the "virtus coeli" generating a new form, or through the qualitative change of alteration. Since each element and mixture has its own natural place in the hierarchy of material substances, and this place is determined by its nature, changes of nature due to a change of the form can produce local motion. If before change the substance is in its natural place, it need not be afterwards, and if not, would then tend to move to its new natural place. ”

“ A hypothesis similar to that used to explain electric attraction lay beneath the explanation of magnetic coition: that bodies brought into contact will move together. In electric attraction, the contact is material and due to the "spiritus" from the electric body; in magnetic coition, it is formal and depends on the action of a primary form that spreads from a magnetized body to its limit of effusion, the "orbis virtutis." ”

“ As an Aristotelian considered the substantial form of the element, fire, to act through the qualities of hot and dry, and to cause an upward motion; so Gilbert argued that the substantial form of his element, pure loadstone, acts through the magnetic qualities and causes magnetic coition. This motion is due to its primary form, and is natural to the element earth. [141] It is instilled in all proper and undegenerate parts of the earth, [142] but in no other element. [143]
To the medieval philosopher, the "generantia" of the occult powers of the loadstone are the heavenly bodies. ”

“ According to Gilbert the primary source of matter is the interior of the earth, where exhalations and "spiritus" arise from the bowels of the earth and condense in the earth's veins. [49] If the condensations, or humors, are homogeneous, they constitute the [Pg 131] "materia prima" of metals. [50] From this "materia prima," various metals may be produced, [51] according to the particular humor and the specificating nature of the place of condensation. [52] The purest condensation is iron: "In iron is earth in its true and genuine nature." ”

“ This humoric source of the effluvia was substantiated by Gilbert in a number of ways. Electrics lose their power of electrical attraction upon being heated, and this is because the humor has been driven off. [102] Bodies that are about equally constituted of earth and humor, or that are mostly earth, have been degraded and do not show electrical attraction. [103] Bodies like pearls and metals, since they are shiny and so must be made of humors, must also emit an effluvium upon being rubbed, but it is a thick and vaporous one without any attractive powers. ”

“ In this manner the scholastic restated in philosophical terms the drama of an earth-centered universe.
Although change or motion is normally effected through the above mentioned causal hierarchy, it is not always necessary that actualization pass from the First Cause down through each step of the hierarchy to terminate in the qualities of the individual being. Some of the steps could be by-passed: for instance man's body is under the direct influence of the celestial bodies, his intellect under that of the angels and his will under God. ”

“ Different bodies have different effluvia, and so one has coacervation of different materials. Thus, in Gilbert's philosophy air was the earth's effluvium and was responsible for the unordered motion of objects towards the earth. ”

“ Until several decades ago, the physical sciences were considered to have had their origins in the 17th century—mechanics beginning with men like Galileo Galilei and magnetism with men like the Elizabethan physician and scientist William Gilbert.
Historians of science, however, have traced many of the 17th century's concepts of mechanics back into the Middle Ages. Here, Gilbert's explanation of the loadstone and its powers is compared with explanations to be found in the Middle Ages and earlier. ”

“ Gilbert's second induction was that they are "true and intimate parts of the globe," [78] that is, that they are piece of the "materia prima" of all we see about us. For they "seem to contain within themselves the potency of the earth's core and of its inmost viscera." [79] Whence, in Gilbert's philosophy, the earthy matter of the elements was not passive or inert [80] as it was in Aristotle's, but already had the magnetic powers of loadstone. Being endowed with properties, it was, in peripatetic terms, a simple body. ”

“ Besides the causal hierarchy of forms, the natural world of St. Thomas existed in a substantial and spatial hierarchy. All substances whether an element or a mixture of elements have a place in this hierarchy by virtue of their nature. If the material were removed from its proper place, it would tend to return. ”

“ As to the nature of the primary form itself, Gilbert agreed with Thales that it is like a soul, [195] "for the power of self-movement seems to betoken a soul." [196] With Galen and St. Thomas he placed the form of the loadstone superior to that of inanimate matter. [197] In a sense, Gilbert even made it superior to organic matter, for it is incapable of error. [198] Like the soul, the primary form cannot be fragmented; when a loadstone is divided, one does not separate the poles but each part acquires its own poles and an equator. ”

“ Gilbert was indeed writing a new physiology, both in the ancient sense of the word and the modern. The process of the formation of metals had many biological overtones, for it was a kind of metallic epigenesis. [57] "Within the globe are hidden the principles of metals and stones, as at the earth's surface are hidden the principles of herbs and plants." [58] In all cases, the "spiritus" acts as semen and blood that inform and feed the proper womb in the generation of animals. [59] "The brother uterine of iron," [60] the loadstone, is formed in this manner. ”

“ Conversely, a terrella has all the properties of the earth: [82] "Every separate fragment of the earth exhibits in indubitable experiments the whole impetus of magnetic matter; in its various movements it follows the terrestial globe and the common principle of motion." [83]
The next induction that Gilbert made was that as the magnet possesses verticity and turns towards the poles, so the loadstone-earth possesses a verticity and turns on an axis fixed in direction. ”

“ There are two and only two kinds of bodies that can attract: electric and magnetic. [125] Gilbert refined his position further by arguing that one does not even have magnetic attraction [126] but instead the mutual motion to union that he called coition. [127] In electric attraction, one has an action-passion relation of cause and effect with an external agent and a passive recipient; while in magnetic coition, both bodies act and are acted upon, and both move together. ”

“ One of the few writers whose explanations of the loadstone Gilbert mentioned with approval is St. Thomas Aquinas. Although the medieval scholastic philosophy of St. Thomas seems foreign to our way of thinking, it formed a background to many of Gilbert's concepts, as well as to those of his predecessors, and it will assist our discussion to consider briefly Thomist philosophy and to make its terminology explicit at this point. [17]
In scholastic philosophy, all beings and substances are a coalescence of inchoate matter and enacting form. ”

“ Corruption from external causes may also deform a loadstone or iron so that it can not be magnetized. [186] Bodies mixed with the degenerate substance of the earth or with aqueous humor spoilt by contamination with earth, do not show either electric attraction or magnetic coition. [187]
In a manner suggestive of Peregrinus, Gilbert wrote that, "magnetic bodies seek formal unity." [188] Thus a dissected loadstone not only tends to come back together, as in the unordered coacervation of electric attraction, but to restore the organization it had before dissection. ”

“ The stronger invigorates the weaker, not as if it imparted of its own substances or parted with aught [Pg 132] of its own strength, nor as if it injected into the other any physical substance; but rather the dormant power of the one is awakened by the other's without expenditure. ”

“ Atoms from the loadstone push away the air and tend to cause a vacuum to form outside the loadstone. The structure of iron is such that it, unlike other materials, can be pushed into this empty space by the thronging atoms of air beyond it. ”

“ No science can be based upon faulty observations and certainly much of De magnete was devoted to the destruction of the fantastic tales and occult sympathies of the Romans, the medieval writers, and the Renaissance. However, let us also remember that Gilbert added few novel empirical facts of a fundamental nature to previous observations on the loadstone. ”

“ A bar magnet has greater powers than a spherical one because it tends to concentrate the magnetic powers more in the ends. [162] For a given purity and shape, the heavier the loadstone, the greater its strength. [163] A loadstone has a maximum degree of magnetic force that cannot be increased. [164] However, weaker ones can be strengthened by stronger ones. [165] Similarly, the shape and weight of the iron determine the magnetic force in coition. [166]
The formal forces of a loadstone emanate in all directions from it, [167] but there is a bound to it that Gilbert called the "orbis virtutis." ”

“ Because the earth has the same nature as a celestial globe, its revolution and circular inertia require no more explanation than those of any other heavenly body.
[213] One wonders if Bruno might not have been another of the stimuli for Gilbert. The latter's interest in magnetism began shortly before Bruno visited England and lectured on his interpretation of the Copernican theory. ”

“ The bodies of the globes ... to the end that they might be in themselves, and in their nature endure, had need of souls to be conjoined to them, for else there were neither life, nor prime act, nor movement, nor unition, nor order, nor coherence, nor conactus, nor sympathia, nor any generation nor alteration of seasons, and no propagation ”

“ Those bodies [Pg 137] magnetized by coming within the "orbis virtutis" have in turn an efflux of their own. [176] Iron can also receive verticity directly from the earth without the intervention of an ordinary loadstone. [177] Such verticity can be expelled and annulled by the presence of another loadstone. [178]
Although one does not normally find iron to be magnetized, a loadstone always has some magnetism. That two bodies such as iron and loadstone should have different properties is the result of the loss of a form by the iron, but this form is still potentially present in the iron. ”

“ By virtue of the principle that flows from the magnet to the iron—which principle is potentially in the iron, for the iron already has a foretaste for it—the excited iron could transcend its gravid nature and be preternaturally moved to unite with its principle. ”

“ One can infer that Galen held that all things have, to a greater or lesser degree, a sympathetic faculty of attracting its specific, or proper, quality to itself. [16] The loadstone is only an inanimate example of what one finds in nutritive organs in organic beings. ”

“ After comparing the properties of the loadstone and of iron, his first step in this induction was that the two materials, found everywhere, [69] are consanguineous: [70] "These two associated bodies possess the true, strict form of one species, though because of the outwardly different aspect and the inequality of the selfsame innate potency, they have hitherto been held to be different ..." Good iron and good loadstone are more similar than a good and a poor loadstone, or a good and a poor iron ore. ”

“ Moreover, there is a farther-ranging, though weaker, mutual action of the heavenly bodies so that one has a causal hierarchy of these specific conforming powers. The form of the sun is superior to that of the inferior globes and is responsible for the order and regularity of planetary orbits. ”

“ In hoc autem situ, seu modo positionis, virtutes lapidis huius estimo conservari proprie, et in reliquis sitibus celi virtutem eius obsecari, seu ebetari, potiusquam conservari puto. Per hoc autem instrumentum excusaberis ab omni horologio; nam per ipsum scire poteris Ascensus in quacumque hora volueris, et omnes alias celi dispositiones, quas querunt Astrologi.
As the heavens move eternally, so the spherical loadstone must be a "perpetuum mobile".
Another of the scholars whose explanation of the loadstone Gilbert noted with approval was Cardinal Nicholas of Cusa. ”