The mystics keep telling us that the goal of prayer and the— goal of our hidden life which should itself become more and more of a prayer— is union with God. We use that phrase often, much too often, to preserve the wholesome sense of its awe-fulness. For what does union with God mean? It is not a nice feeling we get in devout moments. That may or may not be a bi-product of union — probably not. It can never be its substance. Union with God means every bit of our human nature transfigured in Christ, woven up into his creative life and activity, absorbed into his redeeming purpose, heart, soul, mind and strength. Each time it happens it means that one of God’s creatures has achieved its destiny.
— From The Light of Christ by Evelyn Underhill (1875-1941)