“For Jesus was not a mere man prior to the communion and union of God with him, but the same Logos, having come into the blessed Virgin herself, took to himself his own temple from the essence of the Virgin. He went forth from her as a man and was seen to be a man externally, although internally, he existed truly as God. Therefore, after his birth, he preserved the virginity of his mother, although this is not true of any of the saints. The saints were by nature human beings and so they all underwent an equally human birth. But, because He was God by nature, when in these last time he also took the human condition, he revealed the birth from the Virgin as different from all other births. Therefore, it is right and just that the blessed one should be called Theotokos and Virgin Mother. For Jesus, who was born of her, was not a mere man. ”
Cyril of Alexandria,
Aganist Those who are unwilling to confess that the Holy Virgin is Theotokos, 5
If you are interested in more quotes on Virgin Mary, you can find them in Against those who are unwilling to confess that the Holy Virgin is Theotokos. or in Mary and the Fathers of the Church on Amazon in both Kindle and paperback formats.
References:
Cyril of Alexandria, C. (2004) Against those who are unwilling to confess that the Holy Virgin is Theotokos. Rollinsford, New Hampshire: Orthodox Research Institute.