If penicillin had been judged by its toxicity to guinea pigs, it might never have been used by man.

My aim is to advocate that we make this mental switch in respect of our attitudes and practices towards a very large group of beings: members of species other than our own - or, as we popularly though misleadingly call them, animals. In other words, I am urging that we extend to other species the basic principle of equality that most of us recognize should be extended to all members of our own species.

Marx saw that capitalism is a wasteful, irrational system, a system which controls us when we should be controlling it. That insight is still valid; but we can now see that the construction of a free and equal society is a more difficult task than Marx realized.

What is there about the notion of a person, at law, that makes every living member of the species Homo sapiens a person, irrespective of their mental capacities, but excludes every nonhuman animal - again, irrespective of their mental capacities?

To turn the other cheek is to teach would-be cheats that cheating pays.

When you look at food as an ethical issue in the Christian tradition, you don't find very much about it. You don't find, as you do in the Jewish or Islamic or Hindu traditions, a lot of restrictions saying you can eat this but you can't eat that. But what you do find is the idea that gluttony is a sin and that it's something that we ought to be ashamed of.

People may hope that the meat they buy came from an animal who died without pain, but they do not really want to know about it. Yet those who, by their purchases, require animals to be killed do not deserve to be shielded from this or any other aspect of the production of the meat they buy.