A man is strolling past the mental
hospital and suddenly
remembers an important
meeting.

Unfortunately, his watch has stopped, and he cannot tell if he is late
or not.
Then, he notices a patient similarly strolling about within the

hospital fence.

Calling out to the patient, the man says, “Pardon
me, sir, but do you
have the time?”

The patient calls back,
“One moment!” and throws himself upon the
ground, pulling out a
short stick as he does. He pushes the stick into the
ground, and,
pulling out a carpenter’s level, assures himself that the
stick is
vertical.

With a compass, the patient locates north and with a steel
ruler,
measures the precise length of the shadow cast by the
stick.

Withdrawing a slide rule from his pocket, the patient
calculates
rapidly, then swiftly packs up all his tools and turns back to
the
pedestrian, saying, “It is now precisely 3:29 pm, provided
today is August 16th,
which I believe it is.”

The man
can’t help but be impressed by this demonstration, and sets
his watch
accordingly.

Before he leaves, he says to the patient, “That was
really quite
remarkable, but tell me, what do you do on a cloudy
day, or at night, when
the stick casts no shadow?” The patient holds
up his wrist and says,
“I suppose I’d just look at my watch.”