You cut a Hydra

Explanation

said of impossibilities; on account of the heads of the Hydra, which Heracles cutting, was no nearer to mastering the Hydra, since she sent up other heads instead of the cut. The Hydra was a huge beast, reared at Lerna, with eight heads, and one middle head immortal. This Heracles slew at Eurystheus' command. Mounting his chariot, with Iolaus driving, he came to Lerna where her lair was; and shooting arrows he forced her to come forth, and seizing the heads cut them off. But he could accomplish nothing; for as one was cut off, two grew up. So calling Iolaus as helper, he ordered him to set fire to part of the nearby wood, and with the brands to sear the places of the cut heads; and in this way, with Iolaus preventing the heads from growing again, Heracles got the upper hand by cutting off the immortal one. Slitting open the Hydra's body and dipping his arrows in her gall, he made them deadly.