annot be corporeal for it travels freely through bodies[134]
and especially magnetic bodies;[135] one can understand the action of
the armature on this basis.[136] Since coition cannot be prevented by
shielding, it must have an immaterial cause.[137]

[133] M: pp. 90, 106, 107, 108, 113, 132, 135, 136, 158. This
is, of course, contrary to modern experience.

[134] M: pp. 106, 107, 108, 114, 134, 136, 140, 162.

[135] M: pp. 106, 109, 114, 159, 162.

[136] M: pp. 137-140.

[137] M: p. 109.

Yet, unless one has the occult action-at-a-distance, change must be
caused by contact forces. Gilbert resolved the paradox of combining
contact forces with forces that cannot be shielded, by passing to a
higher level of abstraction for the explanation of magnetic phenomena:
he saw the contact as that of a form with matter.

Although Gilbert remarked that the cause of magnetic phenomena did
not fall within any of the categories of the formal causes of the
Aristotelians, he did not renounce for this reason the medieval
tradition. Actually there are many similarities between Gilbert's
explanation of the loadstone's powers and that of St. Thomas. Magnetic
coition is not due to any of the generic or specific forms of the
Aristotelian elements, nor is it due to the primary qualities of any
of their elements, nor is it due to the celestial "generans" of
terrestrial change.[138]

Relictis aliorum opinionibus de magnetis attractione; nunc
coitionis illius rationem, et motus illius commoventem
naturam docebimus. Cum vero duo sint corporum genera, quae
manifestis sensibus nostris motionibus corpora allicere
videntur, Electrica et Magnetica; Electrica naturalibus ab
humore effluviis; Magnetica formalibus efficientiis, seu
potius primariis vigoribus, incitationes faciunt. Forma ilia
singularis est, et peculiaris, non Peripateticorum causa
formalis, et specifica in mixtis, est secunda forma, non
generantium corporum propagatrix; sed primorum et praeciporum
globorum forma; et partium eorum homogenearum, non
corruptarum, propria entitas et existentia, quam nos
primariam, et radicalem, et astream appellare possumus
formam; non formam primam Aristotelis; sed singularem illam,
quae globum suum proprium tuetur et disponit. Talis in
singulis globis, Sole, lunas et astris, est una; in terra
etiam una, quae vera est ilia potentia magnetica, quam nos
p