The wings that elevate the Mitzvos: The Zohar states that love and fear of G-d are the wings that elevate the Mitzvos to the upper worlds, and cause their Divine unification [i.e. Yichudim]. This means that the love which motivates the Mitzvah, which is the longing to attach and cleave to G-d, serves as the rocket or propeller for the Mitzvah to reach the supernal worlds. A Mitzvah without this motivation of longing and is like a bird without a wing which is unable to fly above, and the Mitzvah hence remains below under the sun.
 Tanya chapter 40