For the Lord demands of you that you be angry with yourself and engage in battle with your mind, neither consenting to nor taking pleasure in wicked thoughts. The uprooting of sin and the evil that is so embedded in our sinning can be done only by divine power. For it is impossible and outside man’s competence to uproot sin. To struggle, yes, to continue to fight, to inflict blows and to receive setbacks is in your power. To uproot, however, belongs to God alone. If, indeed, you could have done it on your own, what would have been the need for the coming of the Lord? For just as an eye cannot see without light, just as one cannot speak without a tongue, nor hear without ears, nor walk without feet, nor carry out one’s works without hands, so you cannot be saved, nor enter into the kingdom of heaven without Jesus.
(St Macarius the Great,Homilies 3.3,4, in Spiritual Homilies)