Peace be with you!
St. John of the Cross, a Doctor of the Church, was instrumental in developing mystical theology. He was a Carmelite monk.
His works can be found here in the Christian Classics Ethereal Library:
Ascent of Mount Carmel, Dark Night of the Soul, Spiritual Canticle of the Soul and the Bridegroom of Christ (All translated into English--Please click the FREE version plain text UTF-8)
A more exhaustive list can be found here:
It includes his "minor works"