The central conceit of this poem is based around the personification of the moon as a love-struck individual, much as the speaker of the sonnet is frustrated in love. The speaker, in this sonnet, has an imaginary conversation with the moon that allows him to ask the moon if the same ironies of love he experiences on earth are similar in the celestial realm. Note what he asks in a series of rhetorical questions that close the sonnet:
Then ev’n of fellowship, oh Moon, tell me
Is constant love deem’d there but want of wit?
Are beauties there as proud as here thy be?
Do they above love to be lov’d, and yet
Those lovers scorn whom that Love doth possess?
Do they call virtue there ungratefulness?
Note the way in which the comparison of the moon to a lover thwarted in love allows the speaker to draw attention to the bizarre nature of human love. The speaker is clearly very frustrated with human expressions of love, where, he feels, "constant love" is taken not as a positive, but as a profound negative, and the state of being "in love" or "possessed" by love is something to be scorned even when everybody longs for somebody to love them.