rimarium vigorem appellamus. Quare magnetica natura est
telluris propria, eiusque omnibus verioribus partibus,
primaria et stupenda ratione, insita; haec nec a caelo toto
derivatur procreaturve, per sympathiam, per influentiam, aut
occultiores qualitates; nec peculiari aliquo astro: est enim
suus in tellure magneticus vigor, sicut in sole et luna suae
formae; frustulumque; lunae, lunatice ad eius terminos, et
formam componit se; solarque; ad solem, sicut magnes ad
tellurem, et ad alterum magnetem, secundum naturam sese
inclinando et alliciendo. Differendum igitur de tellure quae
magnetica, et magnes; tum etiam de partibus eius verioribus,
quae magneticae sunt; et quomodo ex coitione difficiuntur.

Instead, he declared it to be due to a form that is natural and proper
to that element that he made the primary component of the earth.[139]

To understand his argument, let us briefly recall the peripatetic
theory of the elements. In this philosophy of nature each element or
simple body is a combination of a pair of the four primary qualities
that informs inchoate matter. These qualities are the instruments of
the elemental forms and determine the properties of the element. Thus
the element fire is a compound of the qualities hot and dry, and the
substantial form of fire acts through these qualities. Similarly for
the other elements, earth, water, and air: their forms determine a
proper place for each element, and a motion to that place natural to
each element.[140]

[138] M: p. 105, and Gilbert, _De magnete_, London, 1600, bk.
2 ch. 4, p. 65.

[139] M: p. 105.

[140] M: pp. 289, 322.

Gilbert had previously declared that the primary substance of the
earth is an element. Since it is an element, it has a motion natural
to it, and this motion is magnetic coition. 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]

[141] M: pp. 26, 68, 105, 179, 198, 307, 335, 343. For
rotation, see footnote 147.

[142] M: pp. 67, 71. That each part