It is certainly true that very frequently the joy I have in that the multitude of Thy mercies is made known in me, softens the bitter sense of my great faults. In whom, O Lord, can they shine forth as they do in me, who by my evil deeds have shrouded in darkness Thy great graces, which Thou hadst begun to work in me? Woe is me, O my Maker! If I would make an excuse, I have none to offer; and I only am to blame. For if I could return to Thee any portion of that love which Thou hadst begun to show unto me, I would give it only unto Thee, and then everything would have been 19 safe. But, as I have not deserved this, nor been so happy as to have done it, let Thy mercy, O Lord, rest upon me.
Teresa of Avila, Life, IV.5
The most famous event in Teresa's life is the Transverberation, the subject of the famous sculpture by Bernini. She describes the event in Chapter XXIX:
I saw in his hand a long spear of gold, and at the iron's point there seemed to be a little fire. He appeared to me to be thrusting it at times into my heart, and to pierce my very entrails; when he drew it out, he seemed to draw them out also, and to leave me all on fire with a great love of God. The pain was so great, that it made me moan; and yet so surpassing was the sweetness of this excessive pain, that I could not wish to be rid of it. The soul is satisfied now with nothing less than God. The pain is not bodily, but spiritual; though the body has its share in it, even a large one. It is a caressing of love so sweet which now takes place between the soul and God, that I pray God of His goodness to make him experience it who may think that I am lying.
(The Carmelites celebrate the Transverberation itself on August 26.)