Saint Bernard of Clairvaux

I consider that the blessing of a fuller sanctification
descended upon her [Mary, the Mother of God], so as not only to sanctify her birth, but also to keep her
life pure from all sin; which gift is believed to have been bestowed upon none
other born of woman. This singular privilege of sanctity, to lead her life
without any sin, entirely benefited the queen of virgins, who should bear the
Destroyer of sin and death, who should obtain the gift of life and
righteousness for all.