"Whenever I am weak, then I am strong."
2 Corinthians 12:10
Do not imagine that the important thing is never to be thinking of anything else [during prayer and meditation] and that if your mind becomes distracted all is lost. I have sometimes been terribly oppressed by this turmoil of thoughts, and it is only just over four years ago that I came to understand by experience that thought is not the same thing as understanding. I asked a learned man about this and he said I was right, which gave me no small satisfaction.
For, as the understanding is one of the faculties of the soul, I found it very hard to see why it was sometimes so timid; whereas thoughts, as a rule, fly so fast that only God can restrain them. It exasperated me to see the faculties of the soul, as I thought, occupied with God and recollected in Him, and the thoughts, on the other hand, confused and excited.
As I write this, the noises in my head are so loud that I am beginning to wonder what is going on in it. My head sounds just as if it were full of brimming rivers, and then as if all the water in those rivers came suddenly rushing downward; and a host of little birds seem to be whistling, not in the ears, but in the upper part of the head.
I should not be surprised to know that the Lord has been pleased to send me this trouble so that I may understand it better, for all this physical turmoil is no hindrance either to my prayer or to what I am writing now, but the tranquility and love in my soul are quite unaffected, and so are its desires and clearness of mind.
It is not good for us to be disturbed by our thoughts or to worry about them in the slightest; for if we do not worry and if the devil is responsible for them they will cease, and if they proceed, as they do, from the weakness that we inherit from the sin of Adam, and from many other weaknesses, let us have patience and bear everything for the love of God. … The clacking old mill must keep on going round and we must grind our own flour; neither the will nor the understanding must cease working. … So it is only right that we should have patience … and not blame our souls for what is the work of our weak imagination and our nature and the devil.
-- St. Teresa of Avila, Interior Castle