This brings up the difference between Mechanics, Physicists, and
Mathematicians.

A Mechanic, Physicist, and Mathematician were riding together on a train.
On the way they saw a black sheep standing in a field.

The mechanic said " All sheep must be black!"

The Physicist said  "Some sheep are black."

The mathemetician said "I observed a sheep, half of which I observed to be
black."

-- Lawrence Lile

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics