E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Cast beyond the Moon.
To form wild conjectures. One of Heywoods proverbs. At one time the moon was supposed to influence the weather, to affect the ingathering of fruits, to rule the time of sowing, reaping, and slaying cattle, etc.
I talke of things impossible, and cast beyond the moon.