This excerpt is from The Mystery of Christmas, a lecture she gave to a group of academics. This is even more powerful when one considers her eventual martyrdom in an Auschwitz gas chamber.
Though we know that the vast majority of people seeking assisted suicide are not physically suffering and are still far off from death, they suffer merely at the thought of suffering.
Without God, our suffering is meaningless.
Christ’s suffering and death are continued in His mystical Body and in each of His members. Every man must suffer and die. But if he is a living member of the Body of Christ. his suffering and death will receive redemptive power from the divinity of the Head. This is the objective reason why all the saints have desired to suffer. This is not a pathological pleasure in suffering. It is true, to natural reason it appears as a perversion. But in the light of the mystery of salvation it shows itself to be highly reasonable. And thus the man who is united to Christ will remain unmoved even in the dark night of feeling estranged from, and abandoned by God. Perhaps divine providence is using his agony to deliver another, who is truly a prisoner cut off from God. Therefore we will say: “Thy will be done” even, and particularly so, in the darkest night.
Nature and dignity 