St. John of Sinai. "The Ladder of Divine Ascent". Step 26.
On discernment of thoughts, passions and virtues
1. Discernment in beginners is true knowledge of themselves; in intermediate souls it is a spiritual sense that faultlessly distinguishes what is truly good from what is of nature and opposed to it; and in the perfect it is the knowledge which they possess by divine illumination, and which can enlighten with its lamp what is dark in others. Or perhaps, generally speaking, discernment is, and is recognized as, the assured understanding of the divine will on all occasions, in every place and in all matters; and it is only found in those who are pure in heart, and in body and in mouth.
2. He who has piously destroyed within him the three passions [gluttony, cupidity, vainglory] has destroyed the five [lust, anger, despair, despondency, pride (St. Gregory of Sinai, ch. 91)] too; but he who has been negligent about the former will not conquer even one passion.
3. Discernment is undefiled conscience and purity of feeling.
4. Let no one on seeing or hearing something supernatural in the monastic way of life fall into unbelief out of ignorance; for where the supernatural God dwells, much that is supernatural happens.
5. Every satanic conflict in us comes from these three generic causes: either from negligence, or from pride, or from the envy of the demons. The first is pitiable, the second is disastrous, but the third is blessed.
6. After God, let us have our conscience as our aim and rule in all things, so that we may know which way the wind is blowing and set our sails accordingly.
