Ken Kesey’s 1963 novel, One Flew Over the Cuckoo’s Nest, also raises questions about whether the people running psychiatric asylums are necessarily more sane than their patients. Kesey’s novel shows the cynicism that developed in the twenty years between it and Harvey: its protagonist is more like a dangerous sociopath than a lovable eccentric, while Kesey’s asylum is a place where victims are mirthlessly drained of all personality.

Arsenic and Old Lace is another comedy about eccentrics that appeared about the same time (it was made into a movie the year Harvey appeared on Broadway). It is about two old aunts who invite lonely bachelors home and poison them. The script is available in a 1995 edition, from Dramatists’ Play Service.

John Patrick Shanley is a contemporary playwright who shares a sense of the whimsical and the imaginative with Mary Chase. His best works are collected in 13 by Shanley (1992), available from Applause Theater Book Publishers.

The famous Irish poet William Butler Yates looked into Celtic mythology with his 1892 collection, Irish Fairy and Folktales, which may have been one of Chase’s sources for information about the pooka. Yates’ book is available in a 1995 paperback edition from Barnes and Noble Books.

Shakti Gawain’s book Creative Visualization (1983) is one of the most influential ‘‘self-help’’ books available, based on the idea that serves Elwood P. Dowd in this play: benefiting from turning the imaginary into reality.