Of all the special effects in Wagner’s “Ring” cycle — an epic four-opera saga with fire-breathing dragons, a magic sword, a magic helmet, magic fire, and of course that cursed ring of power that everyone lusts after — the most dazzling one is musical.

Wagner’s ingenious use of short musical themes creates a whole world of gods, heroes, dwarves and giants, and gives them their psychological and mythical depth.

Think “Star Wars,” was the advice of Christine Goerke, the soprano currently starring as Brünnhilde in the “Ring” at the Metropolitan Opera. “So Darth Vader’s coming in: what music do you hear?” she said. “There — you know everything you need to know about Wagner.”

They can be as simple as that. The themes — which came to be known as leitmotifs — can act as simple musical labels, reminding listeners what is what and who is who. But they can also work on a far subtler level. Ready to explore a few? Put on your headphones.