Intellect and excitement are two separate worlds. Intellect--a world cold and settled; excitement--a world seething and impetuous. Man's avoda (service of G-d) is to combine them, unite them. The impetuousness then becomes transformed into a longing, and the intellect into the guide in a life of service and action.
— Rabbi Yosef Yitzchak of Lubavitch (quoted in Hayom Yom, Shevat 12)