St Gregory Of Nyssa - Excerpts from "On The Beatitudes"
Men, whichever of you longs to have sight of absolute goodness, do not lose hope of ever beholding the object of your desire, when you hear that the divine splendor is raised above the heavens, that its glory cannot be told, that its beauty is past telling and its nature cannot be grasped. For what you are able to grasp is the measure within you of the knowledge of God, for he who made you formed you in the beginning, at the same time adorned you with such goodness.
When you were first created God imprinted upon you reflections of his own nature not unlike someone impressing the form of a seal upon wax. Vice, however, poured round this godlike character, has made the good in you of no value, hidden as it is by base coverings. If you, however, by a careful manner of life, were to wash away the filth that has become coated over the soul, your own godlike beauty will shine out. The same sort of thing happens with iron. Once it has been freed of rust by the whetstone, what was previously black now shines out with its own rays to the sun and affords great brilliance.
Your inner man, which the Lord calls the heart, is like that. Once it has scraped off the rust like incrustations that grow on the soul like a sort of evil mold, it will recover its likeness to its archetype and will be good. For good is in all respects like the good. Therefore, whoever sees himself sees within himself the object of this longing and so the pure of heart becomes blessed, for by contemplating his own purity he sees the archetype in the image. In a similar way, those who contemplate the sun in a mirror, even though they do not look straight at the sun, see the sun no less in the ray in the mirror than do those who look directly at the circle of the sun. So too you, even though you be inadequate for the contemplation of the unapproachable light, if you return to the grace of the image which was planted in you at the beginning, you will find what you look for within you.
What is the deity but purity, freedom from passion and separation from every kind of evil? If these things be in you, then assuredly God himself is within you. As soon as the power of reasoning within you is unmixed with any kind of vice, free from passion and separated from all manner of defilement, then you will be blessed by great sharpness of sight, because in your purified condition you will know what, to those who have not been so purified, remains unseen. Once the material mist has been stripped away from the eyes of the soul, you will see in the pure clarity of your heart the ‘blessed vision’ brightly. What then is it? Purity, holiness, simplicity, all the lightful rays of the divine nature, through whom God is seen….
There are two distinct ideas contained in the promise of seeing God. The first is actually knowing the nature of him who is totally above us; the second is being mingled with him through the purity of our lives. As to the first manner of knowing, the voice of the saints lays it down as being an impossibility for us. The second the Lord promises to human nature through his present teaching, when he says; ‘Blessed are the pure of heart for they shall see God’ [Matt. 5,8].
But how this purity may be achieved you can discover by examining nearly all the teaching of the gospel. By examining its exhortations one by one, you will find a clear account of the meaning of purity of heart.
“Give me a word!”
[Abba Agathon] also said, 'Unless he keeps the commandments of God, a man cannot make progress, not even in a single virtue.’
-Sayings of the Desert Fathers
St Basil, Bishop of Caesarea in Cappadocia, said; 'I have not known a woman and yet I am not a virgin.' He recognized that the gift of virginity is achieved not so much by abstaining from intercourse with woman as by holiness and purity of soul, which in its turn is achieved through fear of God. The Fathers also say that we cannot fully acquire the virtue of purity unless we have first acquired real humility of heart. And we will not be granted true spiritual knowledge so long as the passion of unchastity lies hidden in the depths of our souls.