Much have I travell'd in the realms of gold, (1)
Right from the get-go, Keats lets us know that he's been sporting his explorer's badge for some time now. And he's got the frequent flyer miles to prove it. How does this set-up help us to understand his points about Chapman's translation?
Oft of one wide expanse had I been told (5)
For true explorers, hearing about something is never good enough. Keats won't settle for hearing about Homer—he wants to experience the work for himself.
When a new planet swims into his ken. (10)
Notice that the new planet isn't found by the astronomer, the planet finds him. Sometimes to be an explorer means being receptive enough to be found.