As tension continues to build over the too-high cost we are being asked to pay for the invaluable life of our captured soldier Gilad Schalit, I count my blessings again and again. First, because I cannot even imagine the horror of the Schalit family's agonizing wait. I have no thread of hope, no taunting 'maybe' or 'perhaps' to torture my soul, for I know that I will never see my son again. The last time I saw his too-young, too-innocent face was the night that he and his friends were murdered in the Merkaz Harav library. I identified his body for the police. Second, I know that the terrorist who took my son's life has lost his, stopped in his terrible rampage by a valiant soldier and a brave civilian. So too, I have been spared the agony of wondering how my son's killer has been faring in prison, or on the run from justice. And third, I have been spared the agony of wondering what I would do if my son's killer was to be among those freed in exchange for our captive soldier. NO, I will never need to scan the media for news of his release, nor petition the courts against it. Nor must I ever hope the hope of the simple - that prison had somehow tempered the killer's murderous zeal. And best of all, I will never have to wonder if knowing that the little justice we dared do has been undone could tempt me to settle accounts myself. Would I, like the terrorist who murdered my first-born, procure a weapon and gather intelligence? Would I park and watch the comings and goings of my target? Would I train in the Judean hills, shooting, loading, shooting again, secure that the noise was too difficult to trace accurately? And when I left on my mission, what would I tell my wife and three living children? Would I kiss them goodbye, or leave unannounced? And what would I tell my son's murderer when I found him? Would I ask my friend from IDF intelligence for a few Arabic phrases before starting off - you know, just enough so that I could be sure he knew who it was who had come to end his life?Ana abu Ibrahim Daud Musa, I am the father of Avraham David Moses? I'm sure that during his time in our prisons, with the free newspapers and radio, he would have learned the names of his eight young victims. And would he care? Might he acknowledge that blood calls for blood - that brutal murder cannot go unpunished? Might he even welcome the bullet which would open the door to his own vision of the hereafter? And afterwards, when I sat with the police and informed them that yes, justice had been done, what would they say? As they placed me in handcuffs, would they know what I told them was true? Would I see relief on the detective's face, knowing that this terrorist, freed in the horrid calculus of prisoner exchange, would never kill again? I am indeed glad that I need not trouble myself with all these tortured imaginings in the days and weeks to come. But I know that the tens, if not hundreds, of families whose lives have been torn asunder by terrorists who may soon walk away from prison will once again lay awake at night and agonize over the meaning of justice in the Middle East. The writer has a PhD in medical history and researches Israeli medical ethics. He is currently completing a book on the Merkaz Harav massacre.