While we are so imperfect, we can understand only in part. The same self-love that causes our defects injuriously hides them from ourselves and from others. Self-love cannot bear the view of itself. It finds some hiding place, it places itself in some flattering light to soften its ugliness. Thus there is always some illusion in us while we are so imperfect and have so much love of ourselves.
Excerpted from a letter to the Countess of Gramont, March 21, 1692:
Take up again the readings that have touched you. They will touch you again, and you will get more out of them than the first time. Bear yourself without flattering yourself or becoming discouraged. This happy medium is rarely found. We promise ourselves great things of ourselves and of our good intentions, or else we despair of all. Hope for nothing from yourself. Look for everything to God. Despair of our own weakness, which is incorrigible, and unlimited confidence in the power of God, are the true foundations of every spiritual edifice. When you will not have much time to yourself, do not miss making use of the least moments which do remain yours. It does not take much time to love God, to renew yourself in his presence, to lift your heart to him, or to adore him from the depths of your heart, to offer to him what you are doing and what you are suffering. This is the true Kingdom of God within us, which nothing can trouble.