So far, St Teresa has stressed the need for humility in order to become perfect in love. But now she turns to the importance of obedience. Obedience does the will of one's superior. Obedience surrenders my will to the command of another. Why is this so crucial?

If we want to open ourselves to God'a activity in the fourth mansions, we must let go of always doing things according to our own will and judging others according to our own viewpoint. There is a danger at this point in the spiritual life of self-reliance and self-will. We need great humility to obtain this obedience. We need to submit our wills to the will of another, to the will of a spiritual guide. Such obedience will help us not look down on others, but look to our ourselves and the Lord.

What is spiritual perfection for the Christian? Having consolations? Doing moderate amount of penances? Taking great care of our bodies? No. Christian perfection consists in the increase of love. St Teresa wants us to fix our minds on this target, this goal. We must surrender ourselves to God, not focus so much on calculating our own perfection. The journey we are on is towards Love, towards becoming a loving person. Great humility makes the journey possible. Focusing on the goal assures success.

St Teresa gives several examples from the world of business to help her friends see what failing to resign oneself to God's will looks like. She wants us to pray for the grace of healing, healing for our wounded souls. So often we want things just according to our taste. We so often fail to surrender to God's plans. We can even get discouraged at the lack of progress we have made. In all these matters, she wants us to practice humility, surrendering ourselves to God.

Jesus said: "I am gentle and humble in heart." St Paul says: "He humbled himself, taking on the form of a servant." Our Lord tells us to take his yoke upon ourselves and to learn from him. 

Humility undermines pride, the great enemy of the spiritual life. In the third mansions, because of our successes and progress, we can become blind to our own limitations and imperfections. We can secretly think that our well regulated life is our own doing. Let us pray not to get ourselves stuck in this stage. God sends us tests and troubles and withdraws certain little graces to help us grow in self-knowledge and humility.

St Teresa gives us a famous description of the regularity of a certain soul that has entered the third mansions. One sign of God's activity is how he fills us with a desire not to commit even a venial sin. Another sign of this stage is aridity in prayer.

Our faithfulness and success is doing good work can lead us to be impatient with God's new activity. The careful self regulation of this stage can make us restless in times of dryness in prayer. St Teresa is warning us about the great need for humility. The devil has his tactics in the third mansions. No complaining. God is leading us into the desert to gain many virtues. Humility is the virtue at the foundation of a great spiritual edifice. 

St Teresa explains why it is a great thing to experience God's action in the third mansions. But her treatment begins with a confession of her own past mistakes. She wants us to apply what she says about herself to ourselves. We are progressing, but we have not reached the summit just yet. One marker of God's new activity in these third mansions is our conscious desire to imitate Mary.

We must consult others in the face of temptations, above all, Our Lord. How do we look to Jesus? Prayer! She explains why we must never to give up on prayer.

If we fall, we must begin again. Prayer is the way to heaven. Prayer requires us to enter into ourselves. Prayer puts us into vital contact with Jesus, the Way to the Father. Prayer is the door to enter this interior castle. Our Lord is not far away. He is within, at the centre of our soul. To teach us how to focus on Our Lord, we have the the Anointing, the Holy Spirit Himself.

The only thing to be really on guard against is giving up!

The second mansions describe our beginning to live a devout life. What happens when we decide to live a more regular life of prayer? What happens when we first want to make up for our old way of life? The devil throws up all kinds of obstacles. The world objects. Our own fallen nature causes troubles. This section is a great exhortation to perseverance. 

St Teresa specifies that the mansions have many rooms. She gives very concrete advice on how to avoid the tricks of the devil in the rooms of this first mansion. She especially explains how the devil loves to cause a cooling of charity in communities by having people focus on things that are not really their concern, especially the perceived faults of others. Powerful warning about the value of charity for a life of prayer.  Very important for understanding the rest of the book.