Besides his deep and profound theological writings, Saint Maximus the Confessor also wrote much on spiritual and ascetical themes. His most famous spiritual work is probably the Four Centuries on Love, which is included in the Philokalia, the greatest collection of spiritual writings of Eastern Orthodoxy. There is more written by Saint Maximus in the Philokalia than by any other writer.
At about the same time, Saint John Climacus (d. 649), abbot of the Monastery of Saint Catherine on Mount Sinai, wrote one of the greatest, classic works on the spiritual life, called The Ladder of Divine Ascent. This book was held in such high esteem that it gave John his last name, for “Climacus” means “of the Ladder.”