INTRODUCTION
receiving an affirmative reply, she at once said : " Then can He
make a stone so heavy that He can't lift it ?" Many wide-awake
grown-up people do not at once see a satisfactory answer. Yet the
difficulty lies merely in the absurd, though cunning, form of the
question, which really amounts to asking, " Can the Almighty
destroy His own omnipotence ? " It is somewhat similar to the
other question, " What would happen if an irresistible moving body
came in contact with an immovable body ? " Here we have simply
a contradiction in terms, for if there existed such a thing as an
immovable body there could not at the same time exist a moving body
that nothing could resist.
Professor Tyndall used to invite children to ask him puzzling
questions, and some of them were very hard nuts to crack. One
child asked him why that part of a towel that was dipped in water
was of a darker colour than the dry part. How many readers could
give the correct reply ? Many people are satisfied with the most
ridiculous answers to puzzling questions. If you ask, " Why can we
see through glass ? " nine people out of ten will reply, " Because it
is transparent," which is, of course, simply another way of saying,
" Because we can see through it."
Puzzles have such an infinite variety that it is practically impossible
to divide them into distinct classes. They often so merge in
character that the best we can do is to sort them into a few broad
types. Let us take three or four examples in illustration of what I
mean.
First there is the ancient Riddle, that draws upon the imagination
and play of fancy. Readers will remember the riddle of the
Sphinx, the monster of Boeotia who propounded enigmas to the
inhabitants and devoured them if they failed to solve them. It was
said that the Sphinx would destroy herself if one of her riddles was
ever correctly answered. It was this : " What animal walks on
four legs in the morning, two at noon, and three in the evening ? "
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