From "My Life with the Chimpanzees" by Jane Goodall:
"Why should we bother about the way animals are treated? Does it matter? After all, there are a lot of humans who are treated very badly. Shouldn't we try to help them first? Of course, we must try to help suffering human beings. But suppose I ask you why? Why does it matter if fellow human beings suffer? They belong to the same species as you and me, so that we know that they have feelings like our own. We know that they can feel pain, as we do. We know that they can feel sadness, fear, despair, loneliness, boredom. Well, so can chimpanzees. And so can dogs and cats and pigs and oh! so many others..."