Part 79 of DoC: St. Leo the Great and Perfection

Blessed are the pure in heart, for they shall see God...  Great is the happiness, beloved, of him for whom so great a reward is prepared. What, then, is it to have the heart pure, but to strive after those virtues which are mentioned above? And how great the blessedness of seeing God, what mind can conceive, what tongue declare? And yet this shall ensue when man's nature is transformed, so that no longer in a mirror, nor in a riddle, but face to face 1 Corinthians 13:12  it sees the very Godhead as He is 1 John 3:2, which no man could see ; and through the unspeakable joy of eternal contemplation obtains that which eye has not seen, nor ear heard, neither has entered into the heart of man.  Rightly is this blessedness promised to purity of heart. For the brightness of the true light will not be able to be seen by the unclean sight: and that which will be happiness to minds that are bright and clean, will be a punishment to those that are stained. Therefore, let the mists of earth's vanities be shunned, and your inward eyes purged from all the filth of wickedness, that the sight may be free to feed on this great manifestation of God. For to the attainment of this we understand what follows to lead.

What St. Leo is describing is the Illuminative State, wherein, those who have been through purification, willingly accepting the suffering necessary to become pure, finally have an illumined mind, conscience, heart, soul, will.

At this stage, one begins to see one's relationship with God as love and experience a power and clarity of mission as never before.

It would be wished that most men and women who are working in and for the Church would attain this level of grace before actually working. 

Goodbye to Leo, for now And, one to the next set in a few days. St. Leo is not one of the Latin Fathers, but as his papacy and that of St. Gregory's are probably the most important in the classical period, I have put them in the same grouping.