Action is the real measure of intelligence.
Napoleon Hill 
A woman uses her intelligence to find reasons to support her intuition.
Gilbert K. Chesterton 
All intelligent thoughts have already been thought; what is necessary is only to try to think them again.
Johann Wolfgang von Goethe 
To predict the behavior of ordinary people in advance, you only have to assume that they will always try to escape a disagreeable situation with the smallest possible expenditure of intelligence.
Friedrich Nietzsche