There are three kinds of physicists ...
the machine builders, the experimental
physicists, and the theoretical physicists.
...
If we compare this with the discovery of America,
then, I would say, the machine builders correspond
to the captains and ship builders who really
developed the techniques at that time.
The experimentalists are those fellows ...
who sailed to the other side of the world
and jumped upon new islands
and just wrote down what they saw.
The theoretical physicists are those fellows
who stayed back in Madrid
and told Columbus he was going to land in India.
--- Victor Weisskopf
http://www.fnal.gov/pub/ferminews/ferminews03-06-27/p2.html