The goal of Medieval mysticism (as with all mysticism as it has appeared throughout the ages) was "union with God." This was the highest ideal of the saints. But such union with God could come about only through rigorous spiritual and physical exercises. It required of one that he (or she) meditate unceasingly on the suffering Christ; that the world with all its attractions be forsaken; that sin be rigorously suppressed by fierce ascetic practices, for only in this way could one escape from what was called "the dark night of the soul." Emerging from this dark night, one awoke to glorious, unearthly, supremely blessed union with God Himself. This is what Catherine meant by her marriage to Christ.

Union with Christ is taught by Scripture as the blessedness of salvation. The joy and comfort of the assurance of salvation is the experience of God's people. Meditation and study of God's Word are held before us as obligatory for a godly life. Genuine piety and a life of fellowship with God is the portion of the righteous even here in the world.

http://www.ccel.org/ccel/catherine/dialog.txt
http://www.prca.org/books/portraits/cather.htm