A bird in the hand is a certainty, but a bird in the bush may sing. (Bret Harte)
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)
We cannot glimpse the essential life of a caged animal, only the shadow of its former beauty. (Julia Allen Field)