IACTA ALEA EST questions

A colleague in the Law School asks me:

Why did Caesar (as reported by Suetonius *Caesar 32) use the singular
in his famous aleatory remark?  Is there a significance to the sort of
game that was played with one die, as opposed to more than one?

Plutarch's *Life of Caesar says that this is a proverbial expression.  Was
it proverbial before Caesar, or did it become proverbial between the time
of Caesar and Plutarch?

Thanks for any light you can shine on these questions.

Daniel Levine
Professor, Classical Studies
University of Arkansas
dlevine@xxxxxxxx