I'm reading The Interior Castle (El Castillo Interior) written by St Teresa of Avila in 1578 A.D. St Teresa was a Carmelite Nun and Christian Mystic who lived in Spain during the Inquisition. This controversial book is a sensual voyage via prayer, fasting and meditation into our inner most being where Christ dwells.
Drawing from the "Mansion of Many Rooms" in John 14:2, St Teresa compares our body to a diamond castle with millions of rooms, and the outer rooms are filled with slithering reptiles and nasty things that keeps us from voyaging inside. Christ dwells in the center of our Interior Castle and we must voyage through seven chambers (of increasing beauty) to reach the Beloved (Jesus). Through devout prayer, meditation, and labor we can have an intimate relationship with Christ that is unparalleled by any earthly friendship, relationship or marriage.
Timothy Keller has a three-minute audio review of this book titled: Jesus as Lover. Keller addresses accusations that Christian Mysticism is repressed sexuality, and explains why this book is so controversial!