Conferences of St. John Cassian - Conference Eleven on Perfection

Cassian describes his initial travels to Egypt with Germanus and their first encounter with Abba Chaeremon, and man of great age and holiness and seek a word from him regarding the path to perfection.  Acknowledging their desire for God, the old man agrees and settles down to speak of the three things that forestall vicious behavior, namely, fear of punishment, hope of reward, and love.  To the three checks on evil there correspond three virtues - faith, hope and love.  The virtues in question are all directed toward a good end, to be sure, but they are not all equally excellent, for they correspond in turn to three significantly different states: Fear belongs to the condition of a slave, hope to that of a hireling and love to that of a son.  Only those who have attained to the image and likeness of God may be numbered in the third state, which is the noblest.  
Persons who avoid vice out of fear are far less stable in virtue than are those who do so out of love.  The former acts as if coerced and when the coercive element is no longer present they cease to be attracted to the good.  The latter, however, are drawn to the good for its own sake.  
Persons who are moved by love also will have in particular the gift of compassion for others in their weakness, realizing that they themselves are utterly dependent upon divine mercy and grace.