Come Sleep! O Sleep, the certain knot of peace, The baiting place of wit, the balm of woe, The poor man's wealth, the prisoner's release, The indifferent judge between the high and low; (1-4)
The speaker reminds us twice in the first line alone that Sleep is a supernatural being and his only hope. The parade of metaphors in the ensuing lines (knot, baiting place, balm, wealth, release) only makes Sleep seem more magical or supernatural: he's real and he can also be all those things?
With shield of proof, shield me from out the prease Of those fierce darts Despair at me doth throw; (5-6)
The speaker's supernatural poem becomes more and more supernatural. If before we just had Sleep, now we have Despair throwing darts, and we learn that Sleep can use a shield to protect the speaker. We admit, this sounds pretty cool—almost like a fantasy movie or something.
O make in me those civil wars to cease; (7)
This just gets better and better. "Civil wars" is totally a metaphor, but for a split second we imagine actual civil wars taking place inside the speaker. Hey, it's not that ridiculous when you consider that the speaker is talking to Sleep, right?
I will good tribute pay, if thou do so (8)
Sleep is now the equivalent of a supernatural mob-boss who the speaker pays for protection (in the form of sleep). Man, this is getting weirder and weirder.
And if these things, as being thine by right, Move not thy heavy grace, thou shalt in me, Livelier than elsewhere, Stella's image see. (12-14)
We get a double dose of wackiness in these lines. We get the whole bit about Sleep being able to do things for the speaker—he's got a "heavy grace" that can be moved—and we get a bit about an image living inside the speaker. This all sounds super-supernatural to us.