Here, light is almost a living thing, pushing outward into places where nothing has a shape yet. The repeated line "at the edge of form" works like a refrain, and each time it returns, the picture grows a little. Light tenses, flows, gropes toward something "unthought, unknown." Then it meets black holes, which pull its waves into "discordance," a kind of tangled noise.
The turn comes in the last two stanzas. Some of the light's force is lost, but the rest keeps moving and even draws the black holes into a shared "harmonic spectrum," like voices joining a song. The darkness is not destroyed. It is brought into harmony.
The speaker sounds quietly awed rather than anxious. The mood is hopeful and steady, and the repetition feels like a slow build. By the end, the poem suggests that creation happens at the boundary, where new harmonics keep taking shape. It reads as a picture of growth, and it may also be about how any new form comes into being.