Sentence:  Since to part, / Go heavenly Gueſt, <WSD>Ethereal</WSD> Meſſenger, / Sent from whoſe ſovran goodneſs I adore. 
Meaning of the word marked with <WSD> tags:  Pertaining to the hypothetical upper, purer air, or to the higher regions beyond the earth or beyond the atmosphere; celestial; otherworldly.