St Diadochos of Photiki. "On Spiritual Knowledge and Discrimination One Hundred Texts".
41. It is well known that obedience is the chief among the initiatory virtues, for first it displaces presumption and then it engenders humility within us. Thus it becomes, for those who willingly embrace it, a door leading to the love of God. It was because he rejected humility that Adam fell into the lowest depths of Hades. It was because He loved humility that the Lord, in accordance with the divine purpose, was obedient to His Father even to the cross and death, although He was in no way inferior to the Father; and so through His own obedience He has freed mankind from the crime of disobedience and leads back to the blessedness of eternal life all who live in obedience. Thus humility should be the first concern of those who are fighting the presumption of the devil, for as we advance it will be a sure guide to all the paths of virtue.