By Jove, what was I saying?!

Whilst watching Jimmy Doherty in Darwin's Garden the other night (by the bye, part 2 is on 12th March), we came across the idiom "By Jove".

So after a little debate about its origins, I set about to look for it.

We figured it might have some amount of religion connotations, at least in early usage.

Well, it was not what we expected.

Excerpt from Dictionary.com:

1325–75; ME <>Jov- (obl. s. of compound nom. Juppiter father Jove), akin. to deus god; c. Gk Zeús (gen. Diós) Zeus


And it makes sense when you think about it now.