The soul united to God and transformed in him draws from within God a divine breath, much like the most high God himself. And God, abiding in the soul, breathes forth the life of the soul as its exemplar. This I take to be what Paul meant when he said: Because you are children of God, God has sent the Spirit of his Son into your hearts, crying, “Abba, Father;” this is what takes place in those who have achieved perfection. One should not wonder that the soul is capable of so sublime an activity. For if God so favors her that she is made God-like by union with the most Holy Trinity, I ask you then, why it should seem so incredible that the soul, at one with the Trinity and in the greatest possible likeness to it, should share the understanding, knowledge and love which God achieves in himself. How this is possible no other power or wisdom can express, save by explaining how the Son of God obtained this sublime state for us and won for us the power to be the children of God, as he asked of the Father: Father, I desire that where I am those you have given me may also be with me, that they may see the glory you have given me, that is, that they may share with certainty the very task I perform. And then he said: Not for them alone do I ask but also for those who will come to believe in me through their teaching, that all may be one as you, Father, are one in me and I in you, that they may be one in us; that the world may believe that you have sent me. And the glory you have given me I have given them that they may be one as we are. I in them, you in me, that they may be made perfect, and the world will know that you sent me and as you have loved me, so I have loved them.
From a Spiritual Canticle by Saint John of the Cross, priest