St. Athanasius the Great ca. 297-373
All those who have their mind on high, all those who forget the things of the earth, all those who give no care to the flesh… who, to be sure, have mortified their earthly members, having a pure mind and an acute mind’s eye, being yet on earth, these see the sufferings that are in hell, the eternal torments, the everlasting fire, the outer darkness, the weeping and the gnashing of teeth. But they also see the heavenly gifts that God has presented to the Saints: the royal attire, the shining inner chambers, the inexpressible delights and eternal life. What more can I say? Indeed, the greatest wonder of all is that he who has a pure mind also perceives with his inner eyes even God Himself. (Constantine Cavarnos, The Future Life According to Orthodox Teaching, p. 38)