I am only making a rough comparison, but I can find no other which will better explain what I am trying to say than the Sacrament of Matrimony. The two things work differently, for in this matter that we are treating there is nothing that is not spiritual: corporeal union is quite another thing and the spiritual joys and consolations given by the Lord are a thousand leagues removed from those experienced in marriage. (Teresa of Avila: Fifth Mansions: Chapter Four)
‘My child, receive the symbol of our crucified spouse. Follow his footsteps in search of souls. Carry him and his light into the homes of the poor, especially to the souls most in need. Spread the charity of his heart wherever you go and so satisfy his thirst for souls.’ These words express beautifully the whole of our life. If we just live this, we will be holy; we will be spouses of Jesus crucified. (Mother Teresa of Calcutta: Total Surrender)
As we move closer to the Sixth and Seventh Mansions, the marriage metaphor becomes essential for our understanding of the Interior Castle. This metaphor is common in the Bible and other spiritual writings. The marriage metaphor helps us better understand the potential intimacy we can have with God. Teresa reminds us that this metaphor has limitations and is completely spiritual: “The spiritual joys and consolations given by the Lord are a thousand leagues removed from those experienced in marriage.”
To fully appreciate this spiritual metaphor we need to understand Teresa viewed this metaphor through the context of a traditional marriage in 16th century Spain. The three stages of marriage included:
- Brief meetings to determine compatibility.
- A betrothal period.
- The marriage itself.
In the Fifth Mansions we may have had a brief, but powerful, encounter with God (see Silkworms and Butterflies). But this is just an early stage toward becoming fully united in our relationship with Christ. The Sixth Mansions is a betrothal period in which we learn to deeply love Christ. In the Seventh Mansion we become united with Him.
Let’s put this into the context of the entire Interior Castle.
Prayer can be separated into two categories:
- Ascetic Prayer: In ascetic prayer we initiate interaction with God through vocal prayer and meditation. This is also called purgative prayer because of the cleansing effect on our lives. The first three Mansions of the Interior Castle cover this material. For a summary of the teachings in this section see: Tools for Spiritual Growth.
- Mystical Prayer: God drives the activity in mystical prayer. Teresa writes about this in Mansions four through seven.
Then we can separate mystical prayer into two categories:
- Illuminative Prayer: Through illuminative prayer God enlightens our will and understanding. Teresa explains this in the fourth Mansions.
- Unitive Prayer: In Mansions five through seven Teresa writes about unitive prayer. Unitive prayer leads us to a deep and intimate relationship with Christ “where the most secret things pass between God and the soul.” Unitive prayer covers 2/3 of the Interior Castle and is the focal point of the book.
Unitive Prayer is divided into three parts:
- Brief Meetings: A brief time in which we see our future Spouse. (Fifth Mansion)
- Betrothal: The promise to marry and learning to love Christ. (Sixth Mansion)
- Marriage: Union with Christ. (Seventh Mansion)
As we approach the Sixth Mansions, we are at a critical juncture in our Christian life. The potential for deep spiritual union with Christ is within reach. But the devil wants to prevent this union. He wars against us. And this time he makes the poison seem so harmless. Some of us have gotten close the Sixth Mansions and been tricked. A decade later our spiritual life is in shambles and we may not even realize it. But we can recover and find union with Christ.
Jesus Follower, Blogger, Public Speaker. Teresaofavilaturns500.wordpress.com
Teresa of Avila Turns 500 
Interesting thoughts.