But, for his mother’s sake, young Perseus was resolved to dare this terrible adventure, and his bravery brought help from the gods.  The last night before he was to set out Pallas came and showed him the images of the three Gorgons, and bade him not concern himself about the two he could not kill; but she gave him a mirror of polished brass, and told him only to look at Medusa’s reflection on it, for he would become a stone if he beheld her real self.  Then Mercury came and gave Perseus a sword of light that would cleave all on whom it might fall, lent him his own winged sandals, and told him to go first to the nymphs of the Graiæ, the Gorgons’ sisters, and make them tell him the way.