The Rebbe Rayatz of Lubavitch (Yahrzeit was 10 Shevat just passed) taught:
Intellect and excitement are two separate worlds. Intellect - a world cold
and settled; excitement - a world seething and impetuous. Man's avoda is to
combine them, unite them. The impetuousness then becomes transformed into a
longing, and the intellect into the guide in a life of avoda and action.