St Peter of Damaskos. "Book II. Twenty-Four Discourses". XI. Discrimination.
It is excellent to seek advice about everything, but only from those with experience. It is dangerous to ask questions of the inexperienced, because they do not possess discrimination. Discrimination knows when the time is ripe, what means to employ, the inner state of the questioner, what level he has reached, his strength, his degree of spiritual knowledge and his intention, as well as God’s purpose and the meaning of each verse of Holy Scripture, and much else besides. Hence he who lacks discrimination may exert himself enormously, but he cannot achieve anything; while the person who possesses it is a guide to the blind and a light to those in darkness (cf.Rom. 2:19). We should refer everything to such a person and accept whatever he says, even if because of our inexperience we do not see its import as well as we would like. Indeed, he who has discrimination is to be recognized in particular from the fact that he is able to communicate the sense of what he says even to those who do not want to know it. For the Spirit searches things out; and God’s presence has the power to persuade even an unwilling intellect to believe. This is what happened in the case of Jonah (cf. Jonah 1:3), Zacharias(cf. Luke 1:18) and - the monk David, once a brigand, whom the angel prevented from saying anything except the psalms that he recited according to his rule of prayer.