Found Objects

As promised, today's Found Object inspired a famous poem. Your job is to name the object, the poet, and the poem"¦ with an added TWIST this week.
The two-line stanza below is a word jumble. Can you put all the words in the right order as found in the poem (without using Google or any other reference aid as a crutch)?
Tothemysteriouspriestwhoarethesecoming? Otosacrificewhatgreenaltar"¦