Many years ago in a French seaport town, I saw what I still think was a vision of evil. In a grubby cafe a boy of about 11 or 12 was ceaselessly feeding coins into one of the crude gaming machines then available. His eyes were blank, the skin of his face was dry and horribly pale. He looked as if he rarely ate. He was (this was, after all, France) smoking a cigarette. I swore at that moment that I would protect any child under my authority from this influence.

Around the same time I found myself in a famine-stricken country – Somalia – and saw for the first time the great round eyes and swollen stomachs of children dying of hunger. In many ways the worst thing was that I was not shocked or moved enough. I had seen this too many times on TV.

I have known ever since that seeing things on screens desensitises us. There is no doubt. If evil is familiar, it is easier to bear and easier to do. It is in our imaginations that we use our consciences and work out how our actions will affect ourselves and others. Conversation, storytelling and reading strengthen our imaginations.

These games kill our imaginations, which help us to be kind, and replace them with the liquid manure of pure selfishness, which helps us to be cruel.