by Sr. Teresa Forcades (from her blog; English translation by Rebel Girl)
The expression 'give birth to the Light' comes from a 13th century sermon attributed to St. Thomas Aquinas (Lux orta) and recollected in the 17th century by Spanish theologian Maria Jesus d'Agreda, also known as the St. Teresa of the Baroque.
Both authors apply it to the fiat of Mary of Nazareth. How should we understand the Marian expression 'Let it be done unto me according to your Word'? (Lk 1:38). According to these authors, the expression should be understood in relation to the first word that God gave in the Bible, that is: 'Let there be light' (Genesis 1:3). The book of Genesis speaks of a world void and without order. It is on this primeval chaos that God pronounced the 'fiat lux' that gives a beginning and meaning to Creation, but it is not until each of us pronounces with Mary her 'Fiat Mihi' that this meaning is made visible and lights up our corner of the world, our day to day existence. Creation becomes co-creation, joint labor between God and human beings (Rom 8:22), and is unthinkable without the human freedom that makes us interlocutors and partners of God.
God has only one Word and in it is contained all His wisdom. This Word, the Logos that makes intelligible the primeval chaos as well as the daily chaos we find each morning, is a living Word: 'The Light came to their home, but they did not accept Him' (Jn. 1:11).
'Giving birth to Light' presupposes letting oneself be shocked by a proposal of love that does not originate in us, that comes from the outside and challenges us: 'Behold, I stand at the door and knock.'(Rev.3:20). This proposal comes in the most unexpected manner and always takes us by surprise. It always implies a risk and only when we dare to risk it all do we recognize that it is our old friend and find the sweet joy of reunion and the wonder that once again it has managed to surprise us.