"Whom the gods would destroy they first make mad"

In this sentence "whom" is used at the beginning where subject is normally placed, but why is it in accusative case? It's should be in the nominative case right? Please explain.


Solution 1:

Whom the gods would destroy [____ they first make ____ mad].

It's actually a tricky construction because "whom" is a prenucleus, where it's both head of the bracketed noun phrase functioning as object of "destroy", and object of "make" in the nucleus clause.