How does Socrates use metaphors to explain Ion's inspiration?

Socrates explains to Ion that Ion is like a magnet "dangling like a lodestone at the end of a chain of lodestones." Therefore, there is a direct chain of causality between the poem, the muse (Homer), and the poet (Ion) through which the aesthetic virtue of poetry is transmuted. If even one link in that chain were otherwise, Ion would not be inspired.