Full Idea
Diodorus' Master Argument inferred that since what is past (i.e. true in the past) is necessary, and the impossible cannot follow from the possible, that therefore if something neither is nor ever will be the case, then it is impossible.
Gist of Idea
From the necessity of the past we can infer the impossibility of what never happens
Source
report of Diodorus Cronus (fragments/reports [c.300 BCE]) by Michael J. White - Diodorus Cronus
Book Reference
'Encyclopedia of Classical Philosophy', ed/tr. Zeyl,Donald J. [Fitzroy Dearborn 1997], p.185
A Reaction
The argument is, apparently, no longer fully clear, but it seems to imply determinism, or at least a rejection of the idea that free will and determinism are compatible. (Epictetus 2.19)