The theology of the cross, that ‘thin tradition’ stretching back through Luther and Augustine and Paul to find its origins in the Hebrew Scriptures themselves, has often been counterposed to the thicker, yet equally long, tradition of mysticism. In recent years, however, distinctions between these traditions have been expressed less categorically. It is now generally recognized that mysticism cannot be regarded as a single phenomenon. Rather, an understanding of diversity within the mystical tradition is foundational to an adequate appreciation of the richness, not only of mysticism, but of the theology of the cross as well. Ecumenical concerns have provided an incentive for discovering complexities in both traditions, and for breaking down the artificial barriers of long-held prejudices. This may make it possible to perceive ‘mystical theology in Martin Luther and evangelical theology in John of the Cross’.