34. NATURAL HISTORY OF PRECIOUS STONES, &c.
likewise
of Ptolemy, that the virtues of stones come from the planets, stars,
and constellations, through the medium of the pureness of their
complexion. Other opinions might be adduced, but since they rest on no
foundation we may as well pass them by, and accept at once the
above-cited explanation :• seeing that no other theory is so consistent
with truth as that of Hermes and the other astronomers, who lay it down
as established that things below are governed by the influence of
things above."
" Albertus Magnus, who
was the chief and greatest of philosophers, following the method of
natural causes, pretends that the virtue of stones proceeds from the
species and substantial form of the stone itself. For in every
composite body there be certain things that have for their cause the
properties of the elements, such as hardness, weightiness, and the
like; and also there be certain things, as for instance the virtues of
the same, that have for cause the species itself. To take an example,
the Magnet possesses hardness, and a ferruginous colour, and other
similar properties, proceeding from the virtue of its ingredients or
elements; but its power of attracting iron proceeds from the species of
the magnet itself; which same species indicates the aggregate
of the material and the form. This is the opinion of the commentator on
the First Book of the Metaphysics, where he explains that species is
not form merely, but the entire aggregate of the matter and the form
which gives its individual being unto the same matter. For the being
(essence) of all things, according to its own species, has its proper
operation and goodness according to the species in which it is formed
and perfected in its natural being."
"
But the form that gives the species to the matter is more powerful than
the other forms; although frequently, from the indisposition of the
matter to receive it, this form
