One of the most frequent misconceptions which is constantly met in the zoo is the business of regarding the animals as prisoners. This is as false and old-fashioned as if in these days everybody still thought that radio and television sets contained little men who talked, sang and danced inside the sets.

Translated by Gwynne Vevers and Winwood Reade, Man and Animal in the Zoo, Chapter 3 (p. 99), Delacorte Press. 1969