Mary Chase’s “Harvey” has been around for 58 years now, lumbering across the American theatrical landscape with its message of “We’re all a little crazy, aren’t we?”

That’s a good message, and the beloved play makes the point softly and without force. The play is disguised as a comedy, though, and it’s not very funny. It is a relic from a gentler era, when a few mild laughs over the course of an evening were enough to make an audience feel like it had been riotously entertained.

Give the Hale Centre Theatre West Valley cast credit, though: There is energy and vigor to spare in the current production, directed by David Nieman. Michelle Linn Hall and Linda Jean Stephenson play, respectively, Myrtle Mae Simmons and her mother Veta Louise, who are mortified at the behavior of Veta’s brother Elwood, who claims to have a 6-foot invisible rabbit as a friend. Hall and Stephenson are eager and committed, as are the actors in the supporting roles.

Elwood is played by Andrew R. Looney, and a more pleasant Elwood could not be imagined. What makes the play work, when it works, is the endearing nature of this character, and Looney is nearly perfect. When Elwood invites a telemarketer over for lunch, you believe he’s sincere.

He is, however, the only realistic character on the stage. Aside from him, it’s a tableau of caricatures — funny ones, at times, but caricatures still. They don’t react the way real people would react. That’s fine, in moderation, but not stretched out over a three-act play that’s supposed to be meaningful. So much of the dialogue is tangential to the matter at hand — Nurse Kelly (Melissa M. McCune) and Dr. Sanderson’s (Cody K. Carlson) romance, for example — and there’s no compelling reason to pay attention to it.

“Harvey” holds a place near many people’s hearts, and far be it from me to discourage that. Such sentimentalists will find the production nostalgic and adequately played. Others may wonder why it’s still being performed, 58 years later.

Should you go? The cast is enthusiastic, but breathing life into this too-gentle old script is difficult work.