The secret use which was thus made of scientific discoveries
and of remarkable inventions, has no doubt prevented
many of them from reaching the present times; but
though we are very ill informed respecting the progress
of the ancients in various departments of the physical
sciences, yet we have sufficient evidence that almost
every branch of knowledge had contributed its wonders
to the magician’s budget, and we may even obtain
some insight into the scientific acquirements of former
ages, by a diligent study of their fables and their
miracles.
(In the second letter, upon Ocular Illusions, is the
following beautiful passage on the Eye:—)
This wonderful organ may be considered as the sentinel
which guards the pass between the worlds of matter
and of spirit, and through which all their communications
are interchanged. The optic nerve is the channel
by which the mind peruses the hand-writing of Nature
on the retina, and through which it transfers to that
material tablet its decisions and its creations.
The eye is consequently the principal seat of the
supernatural. When the indications of the marvellous
are addressed to us through the ear, the mind may
be startled without being deceived, and reason may
succeed in suggesting some probable source of the illusion
by which we have been alarmed. But when the eye
in solitude sees before it the forms of life, fresh
in their colours and vivid in their outline; when
distant or departed friends are suddenly presented
to its view; when visible bodies disappear and reappear
without any intelligible cause; and when it beholds
objects, whether real or imaginary, for whose presence
no cause can be assigned, the conviction of supernatural
agency becomes under ordinary circumstances unavoidable.
Hence it is not only an amusing but an useful occupation
to acquire a knowledge of those causes which are capable
of producing so strange a belief, whether it arises
from the delusions which the mind practises upon itself,
or from the dexterity and science of others.
(The Optical phenomena, as might be expected, are
most abundant, as they include the subject of spectral
illusions and apparitions, and natural phenomena marked
with the marvellous. The properties of Sound are
next in interest; among them we find explained the
wonder of singers breaking glasses with their great
power of voice; the automaton flute-player, talking
engines, echoes, &c. The Mechanical causes are
less numerous: among them we are glad to see
noticed the feat of lifting heavy persons,
which we ourselves have often seen accomplished; but
Sir David Brewster does not supply the cause.
As the matter may be new to many readers, we quote
the two relating pages.)
