clipped from: www.oceancityfools.com   
Is Your Jar Full?

When things in your life seem almost to much to handle, when 24 hours in a
day are not enough, remember the mayonnaise jar......and the beer.

A Professor stood before his philosophy class and had some items in front
of him.  When the class began, wordlessly, he picked up a very large and
empty mayonnaise jar and proceeded to fill it with golf balls.  He then
asked the students if the jar was full.  They agreed that it was.

So the Professor then picked up a box of pebbles and poured them into the
jar.  He shook the jar lightly.  The pebbles rolled into the open areas
between the golf balls.  He then asked the students again if the jar was
full.  They agreed it was.

The Professor next picked up a box of sand and poured it into the jar.  Of
course, the sand filled up everything else.  He asked once more if the jar
was full.  The students responded with an unanimous "Yes."