By induction, too, our fathers, our grandfathers, knew that it was
impossible for man to traverse the earth faster than at the full speed
of a galloping horse. After several thousand years of experience that
piece of knowledge, which seemed to be singularly certain, was suddenly
proved to be the grossest ignorance by a man who had been in the habit
of playing with a tea-kettle when a boy. We ourselves, not very long
ago, knew positively, as all men had known since the beginning of the
world, that it was quite impossible to converse with a friend at a
distance beyond the carrying power of a speaking trumpet. To-day, a
boy who does not know that one may talk very agreeably with a friend
a thousand miles away is an ignoramus; and experimenters whisper among
themselves that, if the undulatory theory of light have any foundation,
there is no real reason why we may not see that same friend at that same
distance, as well as talk with him. Ten years ago we were quite sure
that it was beyond the bounds of natural possibility to produce a bad
burn upon the human body by touching the flesh with a bit of cardboard
or a common lead pencil. Now we know with equal certainty that if upon
one arm of a hypnotised patient we impress a letter of the alphabet
cut out of wood, telling him that it is red-hot iron, the shape of the
letter will on the following day be found on a raw and painful wound
not only in the place we selected but on the other arm, in the exactly
corresponding spot, and reversed as though seen in a looking-glass;
and we very justly consider that a physician who does not know this and
similar facts is dangerously behind the times, since the knowledge is
open to all.
Pages:
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86