I fully agree with the authoritative teaching of the Catholic Church laid down on 8 December, 1854 by Pius IX that the Blessed Virgin Mary "in the first instance of her conception, by a singular privilege and grace granted by God, in view of the merits of Jesus Christ, the Savior of the human race, was preserved exempt from all stain of original sin."
I differ somewhat in the understanding of this article of faith. Now it seems to me that a human soul develops naturally during pregnancy until it is ready to accept the rational faculty which is infused into the fetus by God (the rational soul may be created brand-new or pre-exist and descend from heaven). Though the soul is fully constructed, owing to the primitiveness of the body, it is at first deaf, dumb, and blind; it acquires its proper powers, i.e., recovers or remembers, slowly as the body develops both before and after birth.
In order to conform to the Catholic teaching, however, we need to posit that Mary's soul, including its rational part, was unusual in coming to be fully present with the body at the instant of conception. As a result, it could be sanctified immediately.
St. Thomas raises the issue, if Mary never contracted the original sin, nor ever sinned actually, why did she need redemption by Christ? This question assumes the "punishment" theory of the Incarnation which I rejected in the previous post and elsewhere.
I have argued that the Incarnation was much more about God the Son than it was about us. It was a brutal gauntlet, a test for Him, whether He would accept the Holy Spirit's grace of love for mankind despite our ultimate injustice against Him personally. We rejected the Son, our greatest benefactor, king, and friend, without whom neither heaven nor paradise could be open to us, utterly and murdered Him. In response, He loved us and brought us unto Himself. I, for example, could not do it. Only the true God could and did.
Again, before the Incarnation, the Son literally did not know whether we were worthy or not, since the opportunity to decide this matter once and for all for Himself, the way to demonstrate His preference in action would arise only in the future at His death. Hence He had no authority to guide the evolution of the communion of saints over the entire duration of their everlasting life. In particular, no finite saint could choose what to study or contemplate in heaven from the Father among an infinitude of all possibilities unaided. Further, paradise is mostly empty in its original state. As I suggested, the first things to be built in it would be "replicators." But what would Moses, say, know about these things? He'd have to learn about them in heaven. Since contemplation could not occur without Jesus, neither could active life: what would be the purpose of allowing people to wander around an empty paradise aimlessly? Keeping the souls awake in Limbo would have been cruel and dangerous, too. So the souls of the dead slept before Christ.
It is for that reason that no one, including Mary, could enter heaven or paradise before the Incarnation. It is irrelevant to this fact that Mary was free of both original and actual sin.
To get back to the title of this post, the Catholic Encyclopedia argues that Mary "was not made exempt from the temporal penalties of Adam -- from sorrow, bodily infirmities, and death." This, too, is at least in part problematic. For Mary had to be gifted not only with a massive amount of grace but also with remarkable bodily health for the sake of her mission as mother of God. Just as her virtue insured Jesus from being aborted, so her physical health insured Him from being miscarried. God could not play dice with the Incarnation. Mary had to be perfectly physically fit for her exalted role.
Therefore, neither Mary nor Jesus contracted any bodily defects through the original sin. However, Jesus assumed those defects of His own free divine will, as suggested in the previous post, while Mary did not. It follows that Mary's earthly body was superior in health and beauty to Jesus' pre-resurrection body. Perhaps like Eve before her sin, she was not going to die of old age through the special solicitude of the Holy Spirit.