Why is the hand symbol used for the hand-cursor?

The question Why is the mouse cursor slightly tilted and not straight? brought up this related question.

Why is the hand symbol used instead of any other symbol, say a spade, for the purpose of a hand pointer?

Then question mark pointer

http://htmlref.com/images/CSS_curs_help.gif

for the what-is/help functionality is logically understandable. But why the hand?