Abstract
The Brabantine mystical author John of Ruusbroec initially appears to be a good example of the problematic relationship between mystics and the Church. He had a conflict with the clerical hierarchy in Brussels during his lifetime. After his death, Jean Gerson, Chancellor of the University of Paris, declared that the third part of Ruusbroec's Spiritual Espousals was to be absolutely rejected. When one examines the historical development of the ecclesial position, it appears that the hierarchy's and the theologians’ concern has an important ethical and ecclesial component. In the ecclesial concern, the unio sine differentia appears to be problematic because it disrupts the unio of human society. An analysis of Ruusbroec's works, however, reveals that nothing could be more alien to his thought than a solipsistic mystic or a contemplative who threatens to endanger the communion of human society. On the contrary, his ideal of the mature Christian mystic is one in whom Christ dwells and who dwells in Christ, and such a person is communion- and community-oriented in every sense. This indwelling has often, however, been misunderstood.