Liberty is given by nature even to mute animals.
Tacitus (55-117 A.D.)

Only that thing is free which exists by the necessities of its own nature, and is determined in its actions by itself alone.
Spinoza (1632-1677)

A bird in the hand is a certainty, but a bird in the bush may sing.
Bret Harte (1836-1902)

All zoos actually offer the public, in return for the taxes spent upon them, is a form of idle witless amusment, compared to which a visit to the state penitentiary, or even a state legislature in session, is informing, stimulating and enobling.
H.L. Mencken (1880-1956)

Man is condemned to be free; because once thrown into the world, he is responsible for everything he does.
Jean-Paul Sartre (1905-1980)

The zoo is a prison for animals who have been sentenced without trial and I feel guilty because I do nothing about it. I wanted to see an oyster-catcher, so I was no better than the people who caged the oyster-catcher for me to see.
Russell Hoban (1925- )

We cannot glimpse the essential life of a caged animal, only the shadow of its former beauty.
Julia Allen Field (1937- )

Human liberation will begin when we understand that our evolution and fulfilment are contingent on the recognition of animal rights and on a compassionate and responsible stewardship of nature.
Dr Michael W.Fox (1937 - )

... You have to love animals for what they are or leave them alone. The best thing you can do for if you love them is leave them alone and see that other people do too.
Pat Derby (1942- )

Wild animals are not meant to be owned, any more than human beings are. Nobody has the right to pass a cougar or a gorilla on from hand to hand.
Pat Derby (1942- )

Suppose that tomorrow a group of beings from another planet were to land on Earth, beings who considered themselves as superior to you as you feel yourself to be to other animals. Would they have the right to treat you as you treat the animals you breed, keep and kill for food?
John Harris (1946- )