en a puzzle to solve by a
friend, but he misunderstood what he had to do, and set about attempting
what most likely everybody would have told him was impossible. But he was
a boy with a will, and he stuck at it for six months, off and on, until
he actually succeeded. When his friend saw the solution, he said, "This
is not the puzzle I intended--you misunderstood me--but you have found
out something much greater!" And the puzzle which that boy accidentally
discovered is now in all the old puzzle books.

Puzzles can be made out of almost anything, in the hands of the ingenious
person with an idea. Coins, matches, cards, counters, bits of wire or
string, all come in useful. An immense number of puzzles have been made
out of the letters of the alphabet, and from those nine little digits and
cipher, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 0.

It should always be remembered that a very simple person may propound a
problem that can only be solved by clever heads--if at all. A child
asked, "Can God do everything?" On 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 sometimes very difficult
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 th