Did Saint Thomas Aquinas Deny the Immaculate Conception? What His Writings Actually Say
A rare relic, the skull of Saint Thomas Aquinas, is currently on a three-week tour of the United States. This is the first time this relic has been available for veneration outside Europe, offering American Catholics a unique opportunity to honor one of the Church's most important theologians.
I was among the faithful who had the chance to venerate the skull of this saint. This relic's tour also coincides with the upcoming feast of the Immaculate Conception of the Blessed Virgin Mary, the Patroness of the United States.
One might be surprised to learn that some Catholics have not fully embraced the visit of Saint Thomas Aquinas’ skull. Is it because of the belief that he rejected the doctrine of the Immaculate Conception?
Is this really true?
Let's explore this perspective and consider how Aquinas, if alive today, would actually defend the doctrine that Mary was conceived without sin.
What is the Immaculate Conception?
In 1854, Blessed Pope Pius IX defined the doctrine of the Immaculate Conception ex cathedra, stating,
“... the most Blessed Virgin Mary, in the first instance of her conception, by a singular grace and privilege granted by Almighty God, in view of the merits of Jesus Christ, the Savior of the human race, was preserved free from all stain of original sin...” (Ineffabilis Deus)
This doctrine states that, unlike the rest of us, Mary was conceived without the original sin inherited by Adam and Eve. Consequently, Mary was free from the inclination to sin and remained sinless throughout her life.
Saint Thomas Aquinas consistently affirmed Mary's sinlessness throughout his writings. For example, early on in his teaching career, he wrote:
“Purity is increased by withdrawing from its opposite: hence there can be a creature than whom no more pure is possible in creation, if it be free from all contagion of sin: and such was the purity of the Blessed Virgin who was immune from original and actual sin” (Commentary on Sentences on Peter Lombard).
So far, so good. Right? Not so fast.
Let us now turn to his later writings, including the Summa Theologica. Some theologians of his time incorrectly believed that Mary's sinless conception meant she didn't need Christ's redemption. In the Summa, he tried to address that misunderstanding.
He proposed that Mary was conceived without original sin, but only after her soul was created and united with her body.
Saint Thomas Aquinas writes:
“If the soul of the Blessed Virgin had never incurred the stain of original sin, this would be derogatory to the dignity of Christ, by reason of His being the universal Saviour of all. But the Blessed Virgin did indeed contract original sin, but was cleansed therefrom before her birth from the womb” (ST, III, 27).
This may seem like an obvious denial of the Immaculate Conception. But he says this because he, and others like Saint Augustine, believed that the soul entered a fetus shortly after conception. They did not have the science that we have today, by which we know that a soul enters a new fetus at the moment of conception.
Furthermore, toward the end of his life, he wrote again that Mary was free of original and actual sin, when commenting on the Archangel Gabriel’s salutation:
"For she (the Blessed Virgin) was most pure in the matter of fault and incurred neither original nor mental nor venial sin."
It's important to remember that the doctrine of the Immaculate Conception was still being debated in Aquinas' time. Like other theologians at the time, he also struggled with the concept, and his views changed over the years.
As we celebrate the Solemnity of the Immaculate Conception, let us appreciate the many centuries of theological debate on the establishment of the feast, including in Saint Thomas Aquinas’ time.
He had a deep devotion to Mary and did his best to defend her honor in explaining her conception. There is little reason to believe that, given all of our scientific and theological advancements, he would not fully support that doctrine as it is understood today.