As if French Jews did not have enough reason to fear for their safety after January's murders, it is difficult for the rest of us to imagine the pain and sadness they must now be feeling. Our thoughts are with them. For ourselves, it is understandable that there is much nervousness and apprehension that it may be a matter of when, rather than if, there is a terrorist attack. But we cannot - we must not - live in fear, constantly looking over our shoulders. It may be a cliché to argue that this would let the terrorists win, but - like most clichés - it is also true.