IMMACULATE CONCEPTION. Title of the Blessed Virgin as sinless from her first moment of existence. In the words of Pope Pius IX's solemn definition, made in 1854, "The most holy Virgin Mary was, in the first moment of her conception, by a unique gift of grace and privilege of almighty God, in view of the merits of Jesus Christ the Redeemer of mankind, preserved free from all stain of original sin." This means that since the first moment of her human existence the mother of Jesus was preserved from the common defect of estrangement from God, which humanity in general inherits through the sin of Adam. Her freedom from sin was an unmerited gift of God or special grace, and an exception to the law, or privilege, which no other created person has received.
Neither the Greek nor Latin Fathers explicitly taught the Immaculate Conception, but they professed it implicitly in two fundamental ways. Mary, they said, was most perfect in purity of morals and holiness of life. St. Ephrem (c. 306-73) addressed Christ and Mary with the words "You and Your mother are the only ones who are totally beautiful in every way. For in You, O Lord, there is no stain, and in Your mother no stain." Mary was described as the antithesis of Eve. Again in Ephrem, "Mary and Eve [were] two people without guilt. Later one became the cause of our death, the other cause of our life." While implicit in the early writers, the Immaculate Conception had to be clarified before becoming explicit dogma. Main credit for this goes to the Franciscan John Duns Scotus (c. 1264-1308), who introduced the idea of pre-redemption in order to reconcile Mary's freedom from original sin with her conception before the coming of Christ. (Etym. Latin im-,not + maculare, to stain.).