This poem's speaker captures impossible love in the cerebral conceit (an elaborate extended metaphor) of "love's whole world" as a globe.
On this globe, the speaker and beloved are doomed to be opposite poles. In this metaphor, the pair can by definition never meet—at least, not unless some huge cataclysm shakes the heavens and the earth and collapses the world into a flat "planisphere," a map upon which the poles might be artificially made to touch.
But it's precisely because the lovers are as distant as the poles that their love can become the axis around which "love's whole world" spins: their love shoots right through the globe between them. This unlikely image uses the language of geography and cartography to depict relationship and connection across an otherwise unbridgeable distance. The poles, here, are linked because they can't be together; their opposition is also what unites them.
Developing the globe conceit further, the speaker and beloved from the poles to the lines of latitude. Like these imaginary lines—which run around the earth in perfectly parallel belts—the lovers' feelings for each other are matched, identical, and "infinite." The problem with parallel lines, of course, is that they "can never meet." This mathematical vision of love suggests that impossibility creates perfection, and perfection creates impossibility:
- On the one hand, this conceit romantically suggests that the most perfect love is one that can never be fulfilled. The fact that the pair go on loving each other in spite of their love's impossibility just goes to show how deep and pure their feelings are.
- On the other, there's a hint here that never getting to consummate one's love might also keep it perfect. More "oblique," slanted, imperfect loves might create an "angle," the speaker suggests—that is, they might touch, the lovers might come together. But they're also not so beautifully matched. The implication might be that the only perfect love is one that never gets lived out; any real-life relationship eventually destroys fantasies of perfection.
The poem's images of "conjunction" and "opposition" paint a picture of impossible love as a problem of inarguable geometry: these are just the facts. As parallel lines can never touch, as a pole is defined by being exactly opposite another pole, so these two lovers are forever aligned and forever separate.