“She shall crush thy head”
From True Devotion by St. Louis de Montfort
“Inimicitias ponam inter te et mulierem, et semen tuum et semen illius; ipsa conteret caput tuum, et tu insidiaberis calcaneo ejus (Gen. iii. 15),—‘I will put enmities between thee and the woman, and thy seed and her seed; she shall crush thy head, and thou shalt lie in wait for her heel.’
“God has never made or formed but one enmity; but it is an irreconcilable one, which shall endure and develop even to the end. It is between Mary, His worthy Mother, and the devil,—between the children and the servants of the Blessed Virgin and the children and instruments of Lucifer. The most terrible of all the enemies which God has set up against the devil is His holy Mother, Mary. He has inspired her, even since the days of the earthly Paradise, though she existed then only in His idea, with so much hatred against that cursed enemy of God, with so much industry in unveiling the malice of that old serpent, with so much power to conquer, to overthrow, and to crush that proud impious rebel, that he fears her not only more than all Angels and men, but in some sense more than God Himself. It is not that the anger, the hatred, and the power of God are not infinitely greater than those of the Blessed Virgin, for the perfections of Mary are limited, but it is, first, because Satan, being proud, suffers infinitely more from being beaten and punished by a little and humble handmaid of God, and her humility humbles him more than the Divine power; and, secondly, because God has given Mary such a great power against the devils, that, as they have often been obliged to confess, in spite of themselves, by the mouths of the possessed, they fear one of her sighs for a soul more than the prayers of all the Saints, and one of her menaces against them more than all other torments.
“God has not only set an enmity but enmities, not simply between Mary and the devil, but between the race of the holy Virgin and the race of the devil; that is to say, God has set enmities, antipathies, and secret hatreds between the true children and the servants of Mary, and the children and servants of the devil. They do not love each other mutually. They have no inward correspondence with each other. The children of Belial, the slaves of Satan, the friends of the world (for it is the same thing), have always up to this time persecuted those who belong to our Blessed Lady, and will in future persecute them more than ever; just as of old Cain persecuted his brother Abel, and Esau his brother Jacob, who are the figures of the reprobate and the predestinate. But the humble Mary will always have the victory over that proud spirit, and so great a victory that she will go the length of crushing his head, where his pride dwells. She will always discover the malice of the serpent. She will always counterwork his infernal mines and dissipate his diabolical counsels, and will guarantee even to the end of time her faithful servants from his cruel claw. But the power of Mary over all the devils will especially break out in the latter times, when Satan will lay his snares against her heel; that is to say, her humble slaves and her poor children, whom she will raise up to make war against him. They shall be little and poor in the world's esteem, and abased before all, like the heel, trodden underfoot and persecuted as the heel is by the other members of the body. But in return for this, they shall be rich in the grace of God, which Mary shall distribute to them abundantly. They shall be great and exalted before God in sanctity, superior to all other creatures by their animated zeal, and leaning so strongly on the divine succour, that, with the humility of their heel, in union with Mary, they shall crush the head of the devil, and cause Jesus Christ to triumph.”