Of what are we speaking when we speak of the Holy Spirit? This most fundamental of all the questions asked in the field of Pneumatology has not received an answer widely accepted in the theology of the twentieth century. Karl Barth could write that the ‘Holy Spirit is nothing else than a certain relation of the Word to man’; while to Rudolph Bultmann, the Spirit was ‘the power of futurity,’ and was to be counted among the mythological forms of New Testament speech. Heribert Mühlen, on the other hand, interpreting the Latin pneumatological tradition in terms of the personalism of Ebner and Bubner, calls the Spirit ‘we,’ the unity of T and ‘thou.’ And David Gelpi reflects current feminist concerns when he designates God's Spirit as ‘The Divine Mother,’ the feminine in God. Finally, most recendy, Michael Welker has adopted the language of the natural sciences mediated through process thought and calls the Holy Spirit a ‘force field,’ while Jürgen Moltmann terms God's Spirit ‘the Spirit of Life’; a notion echoed in Mark Wallace's thesis that the Spirit is ‘the power of life-giving breath (r¨ah) within the cosmos who continually works to transform and renew all forms of life—both human and nonhuman.‘