years they had watched him and tended him, and looked critically for
the least signs of a diminution or an augmentation in his strength. They
knew that he was now in his one hundred and seventh year, and yet he
lived and was no weaker. Was there a limit; or was there not, since the
destruction of the tissues was arrested beyond doubt, so far as the most
minute tests could show? Might there not be, in the slow oscillations
of nature, a degree of decay, on this side of death, from which a return
should be possible, provided that the critical moment were passed in a
state of sleep and under perfect conditions? How do we know that all
men must die? We suppose the statement to be true by induction, from
the undoubted fact that men have hitherto died within a certain limit of
age. 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