This is a poem about love, time and separation. It is addressed to and is about someone who is away. The usual assumption is that the speaker is a woman, because of the domestic metaphors (the housewife and the fly, the balls of yarn), because the writer was a woman, and, I think, because it is traditionally women who wait.
Four of the stanzas begin with "if," a word that indicates uncertainty. This poem plays off certainty and uncertainty against each other. She is certain of her love for him; what she doesn't know is when they will be together and for how long. The time of absence gets longer in each stanza, progressing from fall in stanza one to a year to centuries to eternity in stanza four.
But the length of absence is unimportant, provided his return and their reunion are certain. She dismisses the importance of how long he may be absent by trivializing it; she brushes off the absence of a summer as a housewife would shoo a fly away. "Spurn" connotes contempt or scorn. A year is reduced to months, a smaller unit, and those are compared to balls of yarn to be stored separately. Storing them separately is like counting off individual units, making them more manageable and giving her a sense of control. "Befalls" continues the image of balls. She minimizes a century-long wait by modifying "century" with "only" and calling his absence "delayed." "Delayed" implies that eventually he will return. She counts time on her fingers, rather than on balls. The reference to Van Diemen's land indicates someplace far away. Van Diemen's land is the old name for Tasmania, an island off Australia. Why her fingers would drop is puzzling. One suggestion is that she has in mind a riddle: one person would curl her fingers under and then ask where they had gone; the answer was Van Diemen's Land or "down under."
The fourth stanza introduces a different time, eternity or timelessness. She would willingly die if they would be together forever. She compares her mortal life to a "rind." As the rind is the outer skin which protects the food, so her body (the "rind") contains a spirit or essence which would continue after her death. She continues the food metaphor with "taste." There is a tension and irony in the juxtaposition (placing next to each other) of "If" and "certain." How are these two words incongruous?
The final stanza abruptly introduces a new train of thought, which is indicated by the first word "but." The previous stanzas were hypothetical--if; that is, they discussed imagined possibilities in the future. In this stanza she is in real time, "now." She deals with her reality, which is a frightening one. She calls time "uncertain"; she does not know (is "ignorant") what time or timelessness is or will bring. Her ignorance distresses or "goads" her. She uses the metaphor of a wing for the length of time to pass. The threatening potential of time continues the wing metaphor in her comparison of time to a "goblin bee." The bee threatens with its painful sting. But time's threat is even greater because unstated; it leaves her in uncertainty, doubt, distress. The degree of threat which time presents is suggested by "goblin;" a goblin is at best mischievous, at worst evil.
This is also a poem about anxiety, even dread.
