When Perseus accepted the favor that King Polydectes is asking him, he sat on a lonely place when a voice came to visit him and ask him what's the matter. It was quicksilver, his guest.
Quicksilver was of a great help because of his wits. He taught Perseus how to capture and slay Gorgon Medusa. He used his wits to give Perseus an advantage against Medusa. First he teach Perseus to make his shield shiny as a mirror and then, he helped him meet the 3 gray women who happen to know where the nymphs were, the nymphs who owns the magic wallet, invisible helmet and flying shoes--the things that Perseus needs before going to his plight to slay gorgon Medusa.