In Greek mythology, the Hydra was a terrifying sea monster that had many heads and used them to devour innocent seafarers. Our hero, Heracles, forced the Hydra into the open and began chopping off its heads. But each time a head was severed two new ones grew back. It seemed like a hopeless task but Heracles was undaunted. He finally figured out that if he used a torch to cauterize each severed limb they failed to regrow.