English

Noun

eggs in moonshine ‎(uncountable)

1. A fanciful notion; an unrealistic or ludicrous concept.
   • 1593, Gabriel Harvey, Pierce's Supererogation, or, A New Praise of the Old Ass,

     You may discourse of Hermes' ascending spirit, of Orpheus' enchanting harp, of Homer's divine fury, of Tyrtaeus' enraging trumpet, of Pericles' bouncing thunderclaps, of Plato's enthusiastical ravishment, and I wot not what marvellous eggs in moonshine: but a fly for all your flying speculations when one good-fellow with his odd jests, or one mad knave with his awk hibber-gibber, is able to put down twenty of your smuggest artificial men, that simper it so nicely and coyly in their curious points.

   • 1951, C. S. Lewis, Prince Caspian, Collins, 1998, Chapter 7,

     […] your Majesty knows I think the Horn—and that bit of broken stone over there—and your great King Peter—and your Lion Aslan—are all eggs in moonshine.

Synonyms

• pie in the sky