The men in the illustration are disputing over the liquid contents of a
barrel. What the particular liquid is it is impossible to say, for we
are unable to look into the barrel; so we will call it water. One man
says that the barrel is more than half full, while the other insists
that it is not half full. What is their easiest way of settling the
point? It is not necessary to use stick, string, or implement of any
kind for measuring. I give this merely as one of the simplest possible
examples of the value of ordinary sagacity in the solving of puzzles.
What are apparently very difficult problems may frequently be solved in
a similarly easy manner if we only use a little common sense.
[Illustration]