Zeus made law (no one knows when because it’s only brought up in this story) that no god will be able to undo the actions of another. So, really, he can’t undo what Hera did.
Why make such a law in the first place, though? Most laws in the human world tend to form as part of a reactionary process. Bad things get done, then we finally get our act together and come up with something that says, we shouldn’t do this thing. This thing, whatever it is, is detrimental to society in some fashion.
With Zeus, we don’t see him set up very many laws. There is the law regarding messing with Hestia, the law of hospitality, and now the law about undoing the actions of another god. We’ve discussed the importance of Hestia and the law of hospitality with Odysseus and Polyphemus. We know that when Zeus actually lays down a law, it’s a big deal, like kind of universe-shaking deal.
This latest law we have is on the same level, and potentially universe-ending if not followed. As we’ve seen by examining the other gods, they’re not exactly the most thoughtful and stable bunch. They tend to follow their whims very easily, and lash out in the same way. They also struggle against one another using human proxies.
With Teiresias, Hera takes out her anger against him. With other gods such as Demeter, she lashed out against Erysichthon, causing him an endless hunger. Was it justified? Most of these transgressions generally are not by modern standards. If one of the gods felt that he had been treated poorly, he or she could have undone Demeter’s handiwork and that would be an end to it, except for Demeter’s ire. So what’s the harm?
If Zeus would simply undo what Hera did, what’s to stop her from re-doing it in the first place once Zeus isn’t around? The same goes for Demeter or Athena or Artemis. Where would this undoing and re-doing ever end? No progress would ever be made as everything would be trapped in an endless cycle of reversing the changes done by another.
The other reason concerns the nature of the gods themselves, coming up next week.