The mother of all vices is self-love because it leads directly to “self-praise, self-satisfaction, gluttony, unchastity, self-esteem, jealousy . . . [and] pride” (Hesychios the Priest). Furthermore, self-love hides all the other inordinate passions within it (John Climacus) and leads to avarice (Maximus the Confessor). Self-love resembles a veil covering the soul, especially the nous, the heart of the soul, thus preventing “the world’s foundations – the inner senses (logoi) of things” (Ilias the Presbyter) from being revealed. Curing self-love entails doing the opposite of what this mother of all vices, and its derivative passions, spur one to do.
Met. Hierotheos. (2010). The science of spiritual medicine, pp. 119-122. Greece: Birth of the Theotokos Monastery.