In Wicked, the line “Animals should be seen and not heard” is deliberately left as an in‑universe mystery: neither the stage musical nor the first film definitively states who wrote it on Dr. Dillamond’s blackboard.

What the story confirms

  • The note appears in Dr. Dillamond’s classroom at Shiz and reads “ANIMALS SHOULD BE SEEN AND NOT HEARD,” shocking him so much that he dismisses class.
  • The musical’s story ends without ever revealing the culprit, and current commentary around the movies treats it as one of Wicked’s lingering unresolved questions.

Most popular theory

  • A widely discussed theory is that Madame Morrible wrote it (or ordered it written), since she is closely tied to the Wizard’s anti‑Animal propaganda and has both motive and opportunity within Shiz’s power structure.
  • Fans also sometimes suggest it could have been an anonymous prejudiced student, which would fit the broader climate of rising hatred against Animals in Oz, but this is speculation rather than canon fact.

Link to the Wicked novel

  • In Gregory Maguire’s Wicked novel, a similar anti‑Animal sentiment appears as part of a public “quell” (short poem), and Madame Morrible recites it, making her openly associated with that rhetoric in the book’s version of the story.
  • Because of this novel detail, many viewers treat Morrible as the most likely in‑universe author of the blackboard line in the musical and the films, even though this still is not officially confirmed on stage or screen.

Information gathered from public forums or data available on the internet and portrayed here.