Let us explore St Clare's conception of mystical motherhood - bringing forth Christ.
That Clare is convinced that the faithful soul can and should nurture the indwelling of God is very clear. She talks about how our souls contain Him who cannot be contained by creation. She knows the promises in Scripture made to those who "remain in Him". We are told, "You did not choose me, I chose you and commanded you to bear fruit, fruit that will last". The 'fruit' that Clare wanted to bear, was actually Jesus, the fruit of the womb of Our Lady. This is why the term 'Spouse of the Holy Spirit' was so important to her that she took it from St. Francis and quoted it in her "Form of Life". The fact that they both remind the sisters, that they had 'taken' the Holy Spirit as a spouse is significant. To have 'taken' emphasizes that it is a free choice; An offer was made and accepted. When Our Lady accepted this offer, she conceived the Word. Francis and Clare's use of the phrase 'Spouse of the Holy Spirit' has this implication, the possibility of conceiving the Word interiorly. St. Clare was called the 'footprint of Mary' because she strove to follow her in as complete a way as possible.
In his letter for the 800th centenary of the birth of St. Clare, the Holy Father said:
Clare and her sisters are called "spouses of the Holy Spirit": an expression not common in the Church's history, in which a sister, a nun, is always described as the "spouse of Christ". However, here we have the resonance of some expressions from Luke's account of the Annunciation, which become key words for expressing Clare's experience: the "Most High", the "Holy Spirit", the "Son of God", the "handmaid of the Lord" and lastly, that "overshadowing" which for Clare is her investiture".
(cf. LegCl 8)
The Holy Father goes on to say,
"She did not even notice that through her contemplation and transformation, her womb as a consecrated and "poor virgin" attached to the "poor Christ" had become a cradle of the Son of God."
Here he is referring to an incident mentioned in the Process of Canonization, where one of the sisters sees the Infant Jesus sitting in Clare's lap. It is as if the Lord wants to give some proof to the sisters that Clare had actually conceived and brought forth the Word.
To talk like this might seem almost surreal, however we have the authority of St. Bonaventure to show that, not only is not beyond the bounds of reason, but that, we should aspire to this. He says:
"As I considered these things, it arose mysteriously in my mind that by the grace of the Holy Spirit and the power of the Most High, a soul dedicated to God could spiritually conceive the holy Word of God, and only begotten Son of the Father (and) give birth to him."
Having said all this, how does it actually come about? Well, firstly, all agree that it is the action of the Holy Spirit in the soul, in other words, grace. Jesus has said that, "Whoever does the will of my Father in Heaven, is my brother and sister and mother". For Bonaventure and Clare, it happens in a soul dedicated to God, a faithful soul. For Francis, it is through a pure and sincere conscience. In more recent times, Bl. Columba Marmion would simply say that it happens through purity of intention. He puts it like this:
"How does the Spirit unite us to the Word? By grace and charity. It was by the Spirit that Christ was conceived in the Virgin's womb; and it is by the Spirit, by His grace and love that the fruitfulness of all our work results. The necessary elements of supernatural fruitfulness are sanctifying grace and purity of intention"
(Verbi Sponsa, Ch. VII)
By praying like this St. Clare gave life to many daughters, in her own life and down to our own day. This is our call too. And so, we make our own the prayer of the Holy Father for the friars at their general chapter of 2003, in which, quoting St. Francis, he said:
"May the Holy Spirit, with his light and power make you capable of bearing Christ 'in your heart and body through love and a pure and sincere conscience' and of giving birth to him 'through a holy activity, which must shine before others as an example'
(Francis, Lettera a Tutti I Fedeli, X, 53)"