If St Teresa helps us to understand and appreciate the importance of spiritual oases in the desert, St John of the Cross helps us understand and appreciate the importance of desolation. This is why it is important to read them both to get the best possible picture of the way ahead. They are a powerful combination, because they were totally orthodox and safe guides who detailed, in two unique but complementary ways, the purification or the purgatory on earth that takes place on the mystic way. They show in different ways how God works through presence and absence, through light and darkness, through death and resurrection, to purge away everything that prevents a person from entering into an ever-fuller union with himself.
Once this purification is completed, the union for which the believer craved from the beginning can take place immediately. The very moment that selfishness has been sufficiently purged away is the moment when the necessary likeness to Christ enables the two to become one. Then, for the first time, the mystic can genuinely say, with St Paul, ‘I live, no, it is no longer I who live but it is Christ who lives in me.’ In the Dark Night of the Soul, the sensual and the spiritual which were separated at the beginning of the purification are reunited as one at the end of it and are simultaneously reunited with the Christ who was completely lost to view in its darkest moments.