Men are of three kinds: slaves, hirelings or sons. Slaves do not love the good, but refrain from evil out of fear of punishment; this is a good thing, but not fully in accord with God’s will. Hirelings love what is good and hate what is evil, out of hope of reward. But sons, being perfect, refrain from evil, not Out of fear of punishment, but because they hate evil violently; and they do what is good, not because they hope for reward, but because they consider it their duty.

St. Peter of Damaskos