The bombing in London this week was dreadful - not least, to my mind, because it was so cheap and nasty.

There seems to have been a downward scale in all this. 9/11 was the grand gesture, commandeering 747s and crashing them into landmark buildings. Bali was a single bomb on a huge scale, detonated in the back of a parked truck. Madrid was a series of smaller bombs, detonated on trains remotely by mobile phone.

And now, in London, we have - what? Small bombs on tube trains, and one on the top deck of a bus. It seems cheap and mean-spirited to me.

I could be angry, and many people are. I spent an hour arguing with a slightly drunk man about it on the train home last night. But I'm not so much angry as sad - sad that people can drift into a state where they no longer see members of the public, strangers, as other people, but as an abstract representation of everything they hate. How else could they go through with it, if they did not anaesthetise themselves in this way?

The best expression I can recall for the process describes Pharaoh's unwillingness to let the people of Israel go. He 'hardened his heart against them', it says.

That's just it, isn't it? These people have hardened their hearts. God forbid that we should do the same.