One interpretation of "Continuum" is that it is a poem about writing. It is writing about writing. There is an analogy between individual experience as observation and individual writing.
In the first line of the poem, the narrator describes the moon travelling through the sky. The moon is a common symbol of mystery, femininity, madness, and inspiration. Just as he's about to indulge in this Romantic symbol and landscape, the narrator says that he was not actually talking about the moon; he was talking about himself.
In the second stanza, the narrator notes that he can not sleep. At this point, the narrator decides to go for a walk and leans out from the porch into the surrounding environment. The poem ends with the narrator going back inside, walking with "the author."
Turn on a bare
heel, close the door behind
on the author, cringing demiurge, who picks up
his litter and his tools and paces me back
to bed, stealthily in step.
The narrator and the author are two but the same person. In this case, the sleepwalking and inability to "think thoughts" is a case of writer's block. That's a simplistic explanation but has more profound implications for a poet who, like a demiurge, is trying to create or describe a significant moment in the world.
The narrator began the poem in Romantic style, describing a scene in nature perhaps en route to suggesting a sense of universality. But the narrator abruptly moves to a self-reflexive consideration. He attempts to describe objects in his surroundings but finds himself thinking about his own act of creating. He states but also asks (query) that/if the clouds are like dust. One cloud is his and the other is an adversary. He then flippantly or uncertainly says this all depends "on the wind, or something." The writer/narrator, as a demiurge, is caught in some sort of self-reflexive writer's block where he is stuck dwelling on his paradoxical (passive/active) role of observer and creator.
As a philosopher might redundantly think about the experience of experience, Curnow might be writing about writing, or writing about the experience of writing. The extended metaphor is more of an analogy of writing and experience: both involve passive observation and active (conscious) creation of the surrounding world. Therefor, there is a continuum between the poet and the poem just as there is a continuum between the individual and experience/the world. The narrator recognizes that he is like a demiurge; he is of the same stuff that he is experiencing/writing about. Experience and writing are indispensable bridges (continuum) between the individual and the world, or the poet and the poem. In this interpretation, this poem is about that continuum.