OS (Text) -- 15
76 The watchtower of the reasons (logoi) concerning every virtue is the keeping of the mind (nous), as David’s watchman of old made manifest beforehand the circumcision of the heart [cf. 2 Kgs. 13, 34; 18, 24–7].
77 Just as we are damaged when we see with the senses those things which are damaging, thus also in the mind (nous).
78 Just as he who has pierced the heart of the plant has laid dry the whole, thus understand concerning the heart of man. This very moment it is necessary to attend since the thieves are not idle.