As evidenced by the following anecdotal excerpt - compliments of ATXCatholic.com , St Teresa was never short of courage :“Now I have begun to speak about this matter because, as I have said, the harm the devil can here cause is great, and only very slowly is it recognized; thus perfection can be gradually vitiated without one’s knowing why. For if this confessor wants to allow room for vanity , because he himself is vain, he makes little of it even in others. May God, because of who he is, deliver us from such things. A situation like this would be enough to disturb all the nuns because their consciences tell them the opposite of what their confessor does. And if they are restricted to only one confessor, they don’t know what to do or how to be at peace. For the one who should be calming them and providing a remedy is the one who is causing the harm.”
St. Teresa had a lot of instances where she encountered Satan and beat him through the power of God but my favorite instance would have to be this one: One night, Satan appeared to St. Teresa of Avila as she was trying to sleep. When she saw the dark figure before her, she became frightened because she thought it was a burglar or an intruder to harm her or her convent sisters. She then realized that the figure before her was Satan and she then proceeded to say: “Oh, it’s only you. I thought it was someone who could actually harm me.” The devil was left humiliated and powerless to do anything since he was given no fear to exploit.