ectrick bodies become * more firmly indurated; about which hereafter.
These substances draw everything, not straws and chaff only[125], but all
metals, woods, leaves, stones, earths, even water and oil, and everything
which is subject to our senses, or is solid; although some write that amber
does not attract anything but chaff and certain twigs; (wherefore Alexander
Aphrodiseus falsely declares the question of amber to be inexplicable,
because it attracts dry chaff only, and not basil leaves[126]), but these
are the utterly false and disgraceful tales of the writers. But in order
that you may be able clearly to test how such attraction occurs[127], and
what those materials[128] are which thus entice other bodies (for even if
bodies incline towards some of these, yet on account of weakness they seem
not to be raised by them, but are more easily turned), make yourself a
versorium of any metal you like, three or four digits in length, resting
rather lightly on its point of support after the manner of a magnetick
needle, to one end of which bring up a piece of amber or a smooth {49}
[Illustration] and polished gem which has been gently rubbed; for the
versorium turns forthwith. Many things are thereby seen to attract, both
those which are formed by nature alone, and those which are by art
prepared, fused, and mixed; nor is this so much a singular property of one
or two things (as is commonly supposed), but the manifest nature of very
many, both of simple substances, remaining merely in their own form, and of
compositions, as of hard sealing-wax, & of certain other mixtures besides,
made of unctuous stuffs. We must, however, investigate more fully whence
that tendency arises, and what those forces be, concerning which a few men
have brought forward very little, the crowd of philosophizers nothing at
all. By Galen three kinds of attractives in general were recognized in
nature: a First class of those substances which attract by their elemental
quality, namely, heat; the Second is the class of those which attract by
the succession of a vacuum; the Third is the class of those which attract
by a property of their whole substance, which are also quoted by Avicenna
and others. These classes, however, cannot in any way satisfy us; they
neither embrace the causes of amber, jet, and diamond, and of other similar
substances (which derive their forces on account of the same virtue); nor
of the loadstone, and of all magnetick substances, w