Saint Augustine on the Immaculate Conception

Having excepted the holy Virgin Mary, concerning whom, on account of the honor of the Lord, I wish to have absolutely no question when treating of sins—for how do we know what abundance of grace for the total overcoming of sin was conferred upon her, who merited to conceive and bear him in whom there was no sin?—so, I say, with the exception of the Virgin, if we could have gathered together all those holy men and women, when they were living here, and had asked them whether they were without sin, what do we suppose would have been their answer?"

― Saint Augustine, Nature and Grace, 36:42._____________________________________________Collect for the Solemnity of the Immaculate ConceptionAlmighty ever living God, who by the Immaculate Conception of the Blessed Virgin prepared a worthy dwelling for your Son, grant, we pray, that, as you preserved her from every stain by virtue of the Death of your Son, which you foresaw, so, through her intercession, we, too, may be cleansed and admitted to your presence. Through our Lord Jesus Christ, your Son, who lives and reigns with you and in the unity of the Holy Spirit, one God, forever and ever. Amen.