This question is an excellent one as it addresses what tools do we have to respond in the face of tragedy, recognizing, that most of us don’t have the actual tools to do what we really desire, which in this question, is to replace the lost limb, turn time back, and allow the person to continue as if the attack didn’t happen. None of us have a magic wand so we can’t do that, but we can do something else. We can, through our words and our thoughts, and our presence, demonstrate empathy and show that the prayers of our tradition, are with you (parenthetically, if you want them to me), during this tragic time.
In the Talmud, in Berachot 5b we read the following:
Rabbi Hiyya bar Abba fell ill and Rabbit Yohanan went in to visit him. He said to him: Are your sufferings welcome to you? He replied: Neither they nor their reward. He said to him: Give me your hand. He gave him his hand and he raised him. Rabbi Yohanan once fell ill and Rabbi Hanina went in to visit him. He said to him: Are your sufferings welcome to you? He replied: Neither they nor their reward. He said to him: Give me your hand. He gave him his hand and he raised him. Why could not Rabbi Johanan raise himself (since we know that he had raised up Rabbi Hiyya bar Abba)? — They replied: The prisoner cannot free himself from jail.
You see, at a time of tragedy what people need is companionship and the knowledge that they are not alone, even if the presenting problem can’t be fixed.
I liken this to the “mi sheberach” prayer often said during services when the Torah is out. When I visit someone in the hospital or I hear that someone is ill, I always ask if they would like their name recited on this list. I don’t recite their name simply because by doing so I can ensure that they will get better (in fact we know that that won’t always happen) but what I can ensure is that their situation is present in our minds. I believe that the prayers that we offer are ones that help the person find the comfort they need to move through their grief as they go from stage to stage.Hopefully these prayers lift them (and their loved ones) up, just as Rabbi Yochanan was able to lift up Rabbi Hiyya bar Abba.
As a modern Jew I believe in God but I don’t depend on God to fix all that is bad (or to create all that is good). If I believed in that world than the world I see wouldn’t look like it does. Rather, I believe that we live in a world where God’s actions can be seen through the good of people. As Rabbi Harold Kushner wrote, “God is in the work of those who offer comfort, those who help with money, with time, with concern. We find God, and we respond to suffering by engaging in work that will better humankind.” Therefore, when we say “our prayers are with you” I believe that we are affirming the sanctity of the person in front of them, that we hope that our religious tradition will bring them the comfort that they are seeking, comfort that only they can truly articulate.