Thoughts on Avot 1:4

"Antigonus, leader of Socho, received the tradition from Shimon the Righteous.  He used to say: be not like servants who serve the master for the sake of receiving a reward; instead be like servants who serve their master not for the sake of receiving a reward.  And may the awe of Heaven be upon you."  (Artscroll translation of Chapters of the Fathers 1:4)

Antigonus is telling us that, in our relationship with God, we should be like forced laborers, not like paid laborers.  We should not see ourselves as God's employees but rather as God's slaves.  What the Artscroll translates as "the awe of Heaven" might be better translated as "the fear of Heaven."  Just as the slave's ultimate motivation for serving his master is fear, so too our ultimate motivation for serving our Master must be fear.  As the Artscroll comments on the phrase "awe of Heaven", "This reverence must be maintained even though one has great love for God, for awe will inhibit one from transgressing His laws, while love not complemented by fear may lead one to take excessive liberties."

If God can be compared to a slave master, He must be compared to a very benevolent slave master, though I would guess that most earthly masters have not been benevolent at all.  A benevolent slave master "gives" many things to his slaves: food, a place to live, clothes, etc.  However, none of these things are given as payment for the slave's labor.  They are given by the master out of his feeling of responsibility for his slaves, out of his personal relationship with his slaves, out of his generosity.  With an employee, on the other hand, no matter how good his relationship with his employer, the paycheck is always given in exchange for the labor.  It's nothing personal, it's a quid pro quo.  For the tzaddik, the blessings that he receives are never received in exchange for the tzaddik's mitzvot; rather, they flow from God's love and generosity.