Seamus Heaney and his Aeneid

The introductory poem from his collection Seeing Things is a translation of a portion of book 6 of the Aeneid.  And, as with all of his poetry, there are memorable highlights, and observations.  But I plucked this one out because its mood and mode matched most closely that of the other excerpt I have made available today:

Day and night black Pluto's door stands open.
But to retrace your steps and get back to upper air,
This is the real task and the real undertaking.