THEOREM VI.

The virtue of the magnet penetrates any solid.

Incitations or movements from magnetic vigor occur despite thick boards, earthenware or glass, marble vessels, nor do waters, vessels, compass boxes, or even fire interposed resist it in the least, which indeed must be considered a supreme miracle of nature; for all interposed things, even if most dense, do not remove its virtue, nor do they obstruct, nor in any way impede, diminish, or retard it. In an iron plate, however, the virtue, being diffused more equally, is diverted in a certain part, which by no reason happens in others possessing attractive power, such as amber, jet, and the like. For these, when an obstacle is placed between them, do not move straw by any reason; indeed, they do not even attract them when brought near unless they are first animated by friction. What the cause of this attraction is, is felt diversely by diverse people. Some conjecture the cause to be certain insensible rays penetrating the pores; others have found the cause to be only sympathy a natural affinity; but even if it were sympathy, sympathy is not the cause, for a passion cannot be called an efficient cause. Scaliger Julius Caesar Scaliger, a Renaissance polymath says more learnedly that iron is moved toward the magnet as toward its matrix, by whose hidden principles it is perfected, just as to the center of the earth, from which D. Thomas Thomas Aquinas (7 Physics) does not differ much. We say that by that vigor with which it permeates the needles that were grasped, as mentioned in Theorem 3, by this same radical vigor and its formal efficiency it penetrates any [medium], almost in the way the sun transmits its rays through even the most solid crystal. But here is an experiment of this virtue.