Part 10

M: p. 105, and Gilbert, De magnete, London, 1600, bk. 2 ch. 4, p. 65.

M: p. 105.

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. It is instilled in all proper and undegenerate parts of the earth, but in no other element.

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

M: pp. 67, 71. That each part is informed with the properties of the whole is an argument favoring an animistic explanation of the nature of this form.

M: p. 109.

To the medieval philosopher, the "generantia" of the occult powers of the loadstone are the heavenly bodies. Gilbert, however, endowed the earth with these heavenly powers which were placed in the earth in the beginning and caused all magnetic materials to conform with it both physically and formally. Such magnetic powers are the property of all parts of the earth; they give the earth its rotating motion and hold the earth together in spite of this motion.

M: pp. 111, 188.

M: pp. 67, 105, 179, 183.

M: pp. 101, 105, 217.

M: pp. 179, 304, 305, 311, 322, 326, 328, 330-334, 338-343.

M: pp. 142, 179; see also electric attraction, p. 97.

Indeed, each of the main stellar bodies, sun, moon, stars, and earth, has such a form or principle unique to itself that causes its parts not only to conform with itself but to revolve. Thus, if one removes a piece of the moon from this body, it will tend to align itself with the moon and then to return to its proper place; and a fragment of the sun would similarly tend to return after proper orientation. 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 like manner, the moon is responsible for the tides of the ocean.

M: pp. 308, 317-343.

M: pp. 106, 340.

M: pp. 308, 309, 311, 330, 333, 344, 347.

M: pp. 136, 334, 345.

By virtue of the causal hierarchy of forms, the loadstone acquires its magnetic powers from the earth. As the earth has its natural parts, so has the stone. Although the geometrical center of a terrella is the center of the magnetic forces, objects do not tend to move to the center but to its poles, where the magnetic energy is most conspicuous. However, in a sense, the energy is everywhere equal: the virtue is spread throughout the entire mass of the loadstone, and all the parts direct the forces to the poles. The poles become the "thrones" of the magnetic powers. On the other hand, the directive force is stronger where coition is weaker and accordingly, verticity is most prominent at the equator.

M: pp. 184-186, 190, 232. This is not quite the same argument as that the powers of the loadstone are identical with those of the earth. See footnote 78.

M: pp. 125, 180.

M: p. 151.

M: pp. 121, 150.

M: pp. 115, 151, 165.

M: pp. 106, 118, 151, 191, 205, 221, 243.

M: pp. 116, 117, 119, 131, 183, 188, 221.

M: p. 31.

M: pp. 116, 151, 200.