"This mystery of God's thirst for union, lived out in the Trinity's eternal embrace, is written in the depths of all being. Not only humanity, but all creation exists for communion. Every entity is drawn to, and exists for, another. From the heart of God to the heart of man, from the spiral of the galaxies drawing their countless stars in a single dance to the entwined double helix of DNA, the Trinitarian mystery of communion is reflected and played out in all that is. The kind of intimacy God offers us, even here on earth, not only approaches our highest experience of human intimacy, but surpasses it." (Joseph Langford) From the bosom of the Trinity, three Persons eternally united in Love, the whole universe has been born. And each one of us bears in our very heart and body the "divine imprint" of the Trinity's own life of love and intimacy; and we are called to return to him through love so that, in communion with him, we may find fulfillment and endless happiness. Earthly spousal love is a dim (but beautiful) reflection of the nuptial form of relationship that God-in the Bridegroom Christ-desires to have with each one of us, and, by uniting himself to us, to draw us into the joy of the Trinity's life. For he loves us with totality, with the gift of his self, whole and entire, in the Paschal Mystery and in the Eucharist (and in prayer and in each moment of life, too!). And he wants to receive all of us, unreservedly, in response, as Saint Francis said: "Hold back nothing of yourself for yourself, so that he who gave himself totally to you may receive you totally." And this total reciprocal gift of persons is oriented towards the complete mutual belonging of the two to one another, giving birth both to the breathtaking joy of intimacy that they share as well as to unimaginable fruitfulness and radiant beauty. In this book I try to unfold, in a condensed and yet thorough way, the heart of Christian prayer, spirituality, and life precisely as the call to nuptial intimacy with God, indeed to intimacy with the Trinity in the joy of his own inmost life. Relying on the rich fabric of Church teaching and the writings of saints and doctors, particularly Teresa of Calcutta and John of the Cross, I seek to create a space in which God can stir into flame-in our own hearts-the longing to respond to his thirst with the complete gift of ourselves, and to shine, by his pure gift, with the beauty of holiness.