been artfully laid for
us.

Occasionally, however, a problem is of such a character that, though it
may be solved immediately by trial, it is very difficult to do by a
process of pure reason. But in most cases the latter method is the only
one that gives any real pleasure.

When we sit down to solve a puzzle, the first thing to do is to make
sure, as far as we can, that we understand the conditions. For if we do
not understand what it is we have to do, we are not very likely to
succeed in doing it. We all know the story of the man who was asked the
question, "If a herring and a half cost three-halfpence, how much will a
dozen herrings cost?" After several unsuccessful attempts he gave it up,
when the propounder explained to him that a dozen herrings would cost a
shilling. "Herrings!" exclaimed the other apologetically; "I was working
it out in haddocks!"

[A] See footnote on page 198.

It sometimes requires more care than the reader might suppose so to word
the conditions of a new puzzle that they are at once clear and exact and
not so prolix as to destroy all interest in the thing. I remember once
propounding a problem that required something to be done in the "fewest
possible straight lines," and a person who was either very clever or very
foolish (I have never quite determined which) claimed to have solved it
in only one straight line, because, as she said, "I have taken care to
make all the others crooked!" Who could have anticipated such a quibble?

Then if you give a "crossing the river" puzzle, in which people have to
be got over in a boat that will only hold a certain number or combination
of persons, directly the would-be solver fails to master the difficulty
he boldly introduces a rope to pull the boat across. You say that a rope
is forbidden; and he then falls back on the use of a current in the
stream. I once thought I had carefully excluded all such tricks in a
particular puzzle of this class. But a sapient reader made all the people
swim across without using the boat at all! Of course, some few puzzles
are intended to be solved by some trick of this kind; and if there
happens to be no solution without the trick it is perfectly legitimate.
We have to use our best judgment as to whether a puzzle contains a catch
or not; but we should never hastily assume it. To quibble over the
conditions is the last resort of the defeated would-be solver.

Sometimes people will attempt to bewilder you by curious littl