The medieval Christian mystics have exerted a powerful influence on Christian spirituality, both Catholic and Protestant, that continues to the present day. Perhaps the most interesting example is that of Eckhart. Seventeen propositions in Eckhart’s teaching were condemned as heretical by Pope John XXII in 1329, but this did not destroy his influence. During the fourteenth and fifteenth centuries, his writings continued to be copied and read in the Dominican and Carthusian Orders. He was known to the author of The Cloud of Unknowing, and his pupils Suso and Tauler continued to interpret his teachings in practical ways for the Christian life.

However, Eckhart’s condemnation ensured that for several centuries his influence was far less than it might otherwise have been. In the early nineteenth century, interest in his writings was revived and scholarly German editions of his work were published. The twentieth century saw a remarkable flowering of interest in Eckhart. Part of this coincided with a growth of interest in Eastern mysticism, and Eckhart’s philosophy has often been compared to Zen Buddhism. The influential Catholic monk Thomas Merton acknowledged his debt to Eckhart, as did psychologist Carl Jung. There is also a consensus amongst scholars today that Eckhart was unjustly convicted of heresy. It is believed that those who examined him were influenced by politics and also had a more shallow understanding of the roots of Christian spirituality than he did.

Eckhart’s disciple Tauler has had a consistently favorable reputation. There appear to be only a couple of exceptions to this, when his works were banned in 1518 by the Jesuits and in 1590 by the Belgian Capuchins for advocating quietism, the idea that the spiritual life consisted of passively resting in a state of mental quietness (a complete misreading of Tauler). But these attacks did not prevent Tauler from having a continuous influence during the Reformation, continuing into the seventeenth and eighteenth centuries.

The other fourteenth-century mystic who today occupies a place of honor only slightly less than Eckhart’s is Ruusbroec. Like Eckhart’s, Ruusbroec’s writings concerning the union of the soul with God were daring, and he was aware that he might be in danger of being thought heretical. Towards the end of the fourteenth century, the last book of his, The Spiritual Espousals, was attacked by the theologian John Gerson, and this temporarily harmed Ruusbroec’s reputation. But during the early years of the Reformation (beginning in the early sixteenth century) and Counter-Reformation (mid-sixteenth century), Latin translations of Ruusbroec’s works were made, and these were intended to encourage people to remain in the Catholic fold. They had the effect of making Ruusbroec well known throughout the continent.

In modern times, Ruusbroec was championed by Evelyn Underhill in her authoritative book, Mysticism (1911). She regarded Ruusbroec as “one of the greatest mystics the world has yet known. In Ruysbroeck’s [sic] works the metaphysical and personal aspects of mystical truth are fused and attain their highest expression.”

William Ralph Inge, author of another influential study, Christian Mysticism (1899), grouped Ruusbroec with Suso, Tauler, and the Theologia Germanica as “the crowning achievement of Christian Mysticism before the Reformation.”

In English mystical literature, The Cloud of Unknowing has always been held in high esteem. It was well known in medieval times since there were many manuscripts in circulation, and this was also true for Hilton’s The Scale of Perfection and many of the works of Rolle. The Cloud of Unknowing has held its reputation to the present day. Clifton Wolters, its most recent translator, describes it as perhaps the greatest devotional classic of the English church: “No one who...