by St. Maximus the Confessor
The one who anoints his mind for the sacred contests and drives away passionate thoughts from it possesses the character of a deacon. The one who illumines it with knowledge of beings and obliberates counterfeit knowledge possesses that of a priest. Finally, the one who perfects it with the holy perfume of the knowledge of a worshiper of the Holy Trinity possesses that a bishop.
(Four Hundred Chapters on Love: Second Century 21)