E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Aganic (4 syl.),
or Aglaonic, the Thessalian, being able to calculate eclipses, she pretended to have the moon under her command, and to be able when she chose to draw it from heaven. Her secret being found out, her vaunting became a laughing-stock, and gave birth to the Greek proverb cast at braggarts, Yes, as the Moon obeys Aganic.