Ν
his commentary on Theophrastus, Sir John Hill touches upon the question
of the medicinal virtues of precious stones. His researches regarding
the causes and conditions determining color in stones, led him to the
conjecture that the active principle, if it really existed, was to be
sought in the coloring matter. As the opinion of a very clever student
in his day, his words will bear quotation :1
The
greatest part of these [medicinal virtues] cannot but be seen at first
view to be altogether imaginary; and as to the virtues of the Gems in
general, it is now the reigning Opinion, that they are nearly all so,
their greatest Friends allowing them no other than those of the common
alkaline Absorbents. However, whether the metalline Particles, to which
they owe their Colours, are, in either Quantity or Quality, in
Condition to have any effect in the Body, is a Matter worthy of a
strict and regular Tryal ; and that would at once decide the Question
between us and the Antients, and shew whether we have been too rash, or
they too superstitious.
The
so-called "doctrine of signatures" treated of the marks set by nature
upon certain objects to denote their usefulness in the cure of diseases
affecting different parts of the body, or their power to neutralize the
effects of the bites of certain animals or reptiles. Of this theory
Martiua says that the ' ' signatures ' ' are not to be sought in a
fanciful resemblance to the form of the objects with the diseased parts
of the human body, but rather in the color, odor, taste, composition,
etc., of the objects.2
1 Theophrastus's " History of Stones," with an English version by John Hill, London, 1746, p. 73.
'Martius, "Unterricht von der Màgi» Naturali, Leipzig, 1717, p. 290.
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