Read the excerpt from “Serenade,” by Edgar Allan Poe. Seven Pleiades entranced in Heaven,
Form in the deep another seven:
Endymion nodding from above
Sees in the sea a second love.

How do the ideas in the excerpt compare to Poe’s ideas in "The Poetic Principle"?

sentence lenght varies according to word choice.you select which word to use and that will require to use other expressions that collocate with the word chosen.sentence length will vary   according to the choice of words you make to express your ideas.  

you know if a word is hiatus if there is a break somewhere in the word