Catherine of Siena contra the Immaculate Conception of Mary

Catherine of Siena (1347-1380) is one of the few female Doctors of the Church in Roman Catholicism.  Suzanne Noffke, O.P. is the editor of a collection of 26 prayers of Catherine of Siena (published by Paulist Press in 1983).  I refer to the translation she provides:

Prayer 16 (lines 10-28)(p. 141):

We are weak because we have received our parents' weak nature. Now parents cannot give their children other than their own, and that nature is inclined to evil because of the rebelliousness of their weak flesh, which they in turn have received from their parents. So our nature is weak and ready for evil evil because we are all descendants and offspring of our first father, Adam, and we have all come from the same clay. Because Adam broke away from you, eternal Father, supreme strength, he became weak. 

Prayer 23 (lines 60-90)(pp. 202-03) 

The eternal Word is given to us through Mary's hands. From Mary's substance he clothed himself in our nature without the stain of original sin-- for that conception was not a man's doing, but the Holy Spirit's. The same was not true of Mary, because she came forth from Adam's clay by a man's doing, not the Holy Spirit's. And since that whole mass was rotten and corrupt, it was impossible to infuse her soul into any but a corrupt material, nor could she be truly cleansed except by the grace of the Holy Spirit. Now the body cannot receive that grace, but only the rational or intellectual spirit. Thus Mary could not be cleansed of that stain except after he soul had been infused into her body-- and this was done out of reverence for the divine Word who would enter that vessel. So, just as a furnace devours a drop of water in a split second, so the Holy Spirit devoured that stain of original sin, for immediately after her conception Mary was cleansed of that sin and given that grace.

Suzanne Noffke points out that Gigli in his edition omitted this section of prayer 23, and that Marracci alleged that this section of the prayer was an addition.  However, Noffke adds that "Marracci's argument is totally without foundation, for the section in question is represented in the earliest manuscripts, long before the edition of 1496 in which he claims the 'addition' was made."(p. 204) She goes on to cite Cavallini as accepting the authenticity of the passage. (p. 205)

Noffke also translated Catherine of Siena's The Dialogue, which was also published by Paulist Press.

Dialogue 14, p. 51

This is why I gave the Word, my only-begotten Son. The clay of humankind was spoiled by the sin of the first man, Adam, and so all of you, as vessels made from that clay, were spoiled and unfit to hold eternal life. So to undo the corruption and death of humankind and to bring you back to the grace you had lost through sin, I, exaltedness, united myself with the baseness of your humanity. For my divine justice demanded suffering in atonement for sin. But I cannot suffer. And you, being only human, cannot make adequate atonement. 

Dialogue 14, p. 52

I really wanted to restore you, incapable as you were of making atonement for yourself. And because you were so utterly handicapped, I sent the Word, my Son, I clothed him with the same nature as yours-- the spoiled clay of Adam-- so that he could suffer in that same nature which had sinned, and by suffering in his body even to the extent of the shameful death on the cross he would placate my anger.

And so I satisfied both my justice and my divine mercy. For my mercy wanted to atone for your sin and make you fit to receive the good for which I had created you. Humanity, when united with divinity, was able to make atonement for the whole human race--not simply through suffering in its finite nature, that is, in the clay of Adam, but by virtue of the eternal divinity, the infinite divine nature. In the union of those two natures I received and accepted the sacrifice of my only-begotten Son's blood, steeped and kneaded with his divinity into the one bread, which the heat of my divine love held nailed to the cross. Thus, was human nature enabled to atone for its sin only by virtue of the human nature.

Dialogue 14, p. 52

Only the scar remains of that original sin as you contract it from your father and mother when you are conceived by them. And even this scar is lifted from the soul--though not completely--in holy baptism, for baptism has power to communicate life of grace in virtue of this glorious and precious blood. 

Notice that the Dialogue, while less explicit than Prayers 16 and 23, but that it provides the conceptual framework upon which Catherine of Siena, a doctor of the Roman Catholic church, denied the error of the immaculate conception, like so many before her.

I am aware that there are some folks out there claiming that Catherine's views from Dialogue 14 and Prayers 14 and 23 are in some way bolstered or reinforced by a purported Marian apparition.  I am not sure from whence they get any such notion.