Animals have this way of constantly confronting us with ultimate questions - about truth and falsehood, guilt and innocence, God and sanctity and the soul - forcing us to define ourselves and our relationship to the world.

My point is that when you look at a rabbit and can see only a pest, or vermin, or a meal, or a commodity, or a laboratory subject, you aren't seeing the rabbit anymore. You are seeing only yourself and the schemes and appetites we bring to the world-seeing, come to think of it, like an animal instead of as a moral being with moral vision.

Animals have this way of constantly confronting us with ultimate questions - about truth and falsehood, guilt and innocence, God and sanctity and the soul - forcing us to define ourselves and our relationship to the world.

When we call something unfair or indecent or unconscionable or evil, when we speak of mercy and pity and compassion, those words have meaning, regardless of our particular faith or moral philosophy. They appeal to common standards we all are expected to understand and accept, standards without which we could not live any common life at all.

If we are defined by reason and morality, then reason and morality must define our choices, even when animals are concerned. When people say, for example, that they like their veal or hot dogs too much to ever give them up, and yeah it's sad about the farms but that's just the way it is, reason hears in that the voice of gluttony. We can say that what makes a human being human is precisely the ability to understand that the suffering of an animal is more important than the taste of a treat.

The smell of factory farms . . . many notice these places only when the odours reach their homes, affecting their own quality of life. We create these animals for our profit and pleasure, playing with their genes, violating their dignity as living creatures, forcing them to lie and live in their own urine and excrement, turning pens into penitentiaries and frustrating their every desire except what is needed to keep them breathing and breeding. And then we complain about the smell.

An author describing the methods of intensive farming, or the excesses of sport hunting, or even the harsher uses of animals in science writes with confidence that most readers will share his sense of concern and indignation. Sounding the call to action-convincing people that change is not only necessary, but actually possible-is more problematic. In protecting animals from cruelty, it is always just one step from the mainstream to the fringe. To condemn the wrong is obvious, to suggest its abolition radical.