Neither fear nor love of self can turn the soul to God; they may sometimes change the aspect or influence the actions of a man, but they will never change his heart.  Even the slave sometimes does God’s work, but because he does not do it willingly he proves that his heart is still hard.  And the hireling too will sometimes od God’s work, but because he only does it for reward, it is clear that he is only attracted by his greed.  Where there is self-seeking, there to is self-esteem; where there is self-esteem, there too is private interest; and where private interest makes a corner for itself there rust and filth will collect.  Let fear itself be the law of a slave, by it he is bound; let greed be for the hireling his law, by it he also is confined when by it he is led off and enticed away.  Neither of these two laws is unspotted, neither can turn the soul to God; only charity can do this, because she alone can make a soul disinterested.  –St Bernard of Clairvaux in a letter to Guigo I, 5^th Prior of La Grande Chartreuse