ces
draw moisture by which their shoots are rejoiced and grow; from analogy
with that, however, Hippocrates, in his _De Natura Hominis_, Book I.,
wrongly concluded that the purging of morbid humour took place by the
specifick force of the drug. Concerning the action and potency of
purgatives we shall speak elsewhere. Wrongly also is attraction inferred in
other effects; as in the case of a flagon full of water, when buried in a
heap of wheat, although well stoppered, the moisture is drawn out; since
this moisture is rather resolved into vapour by the emanation of the
fermenting wheat, and the wheat imbibes the freed vapour. Nor do elephants'
tusks attract moisture, but drive it into vapour or absorb it. Thus then
very many things are said to attract, the reasons for whose energy must be
sought from other causes. Amber in a fairly large mass allures, if* it is
polished; in a smaller mass or less pure it seems not to attract without
friction. But very many electricks (as precious stones and some other
substances) do not attract at all unless rubbed. On the other hand many
gems, as well as other bodies, are polished, yet do* not allure, and by no
amount of friction are they aroused; thus the emerald, agate, carnelian,
pearls, jasper, chalcedony, alabaster, porphyry, coral, the marbles,
touchstone, flint, bloodstone, emery[131], do not acquire any power; nor do
bones, or ivory, or the hardest woods, as ebony, nor do cedar, juniper, or
cypress; nor do metals, silver, gold, brass, iron, nor any loadstone,
though many of them are finely polished and shine. But on the other hand
there are some other polished substances of which we have spoken before,
toward which, when they have been rubbed, bodies incline. This we shall
understand only when we have more closely looked into the prime origin of
bodies. It is plain to all, and all admit, that the mass of the earth, or
rather the structure and crust of the earth, consists of a twofold
material, namely, of fluid and humid matter, and of material of more
consistency and dry. From this twofold nature or the more simple compacting
of one, various substances take their rise among us, which originate in
greater proportion now from the earthy, now from the aqueous nature. Those
substances which have received their chief growth from moisture, whether
aqueous or fatty, or have taken on their form by a simpler compacting from
them, or have been compacted from these same materials in long ages,