Father Sophrony was one of the most respected spiritual figures in 20th-century Eastern Orthodoxy. The phrase "Keep Thy Mind in Hell, and Despair Not" is packed with significance. It can also be seen as an alternative phrasing of what in Buddhism is known as the Four Noble Truths. Perhaps I'll say more about this later.
"Keep thy mind in hell, and despair not." What does it mean to "keep thy mind in hell"? Can it be that we are to use the imagination to conjure up circumstances for ourselves similar to those figures in some primitive painting? In this instance, no. Father Silouan, like certain great Fathers - St. Anthony, St.Sisoe, St. Makarios, St. Pimen - during his lifetime actually descended into the darkness and torments of hell... They took refuge in it when passion - especially the most subtle of passions, pride - reared its head... Blessed Staretz Silouan said that many ascetics when they approached that state - which is vital if one would be cleansed of the passions - would fall into despair and be unable to continue. But the one who knows "how greatly the Lord loveth us" escapes the pernicious effect of total despair and knows how to stand prudently on the verge so that the hellish fire burns away his every passion and does not fall victim to despair. "And despair not." If the Staretz' s account is a simple one, the power and mystery of the matter will remain incomprehensible for anyone who has not known a similar experience of hellish torment, on the one hand, and the great gifts of grace, on the other.
-- Fr. Sophrony