The relationship of the Triune God is intensified by the relationship of "perichoresis". This indwelling expresses and realizes fellowship between the Father and the Son. It is intimacy. Jesus compares the oneness of this indwelling to the oneness of the fellowship of his church from this indwelling. "That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us" (John 17:21). The great 12th century Cistercian reformer St. Bernard of Clairvaux spoke of the Holy Spirit as the kiss of God, the Holy Spirit being thus not generated but proceeding from the love of the Father and the Son through an act of their unified will.