June 13, 1865

The Herne's Egg was the last play Yeats (June 13 1865 to January 28, 1939)  wrote. He finished it in 1938 and said it was influenced by his work with Shri Purohit Swami (1882-1941). They were translating the Upanishads together, on Majorca, at the time.  The Critical Companion to William Butler Yeats (David A. Ross, 2009) records some assessments of The Herne's Egg, including this by Helen Vendler: it is "essentially a rather arid and contrived piece of theatrical writing." Harold Bloom didn't like it either; he said it was "a monument to a mounting confusion and systematic inhumanity of the last phase of Yeats."

In the play we read: "The Great Herne knows 'every man's deed and will meet out a most memorable punishment:' in their next incarnation...[certain] men will be 'pushed down a step or two' and become cat, rat, bat, dog, wolf, or goose."

I cannot pronounce on the play but I rely on the verdict of the Encyclopedia Britannica regarding this art. They said The Herne's Egg was William Butler Yeats' "most raucous work."