Five short lines hold one strange, striking image: a mystery that is exploding outward and twisting its neck right around, trying to look at itself, but failing. It can't see its own face. The poem gives the unknown a body and a kind of desperate curiosity, then denies it the one thing it wants, self-knowledge.
Meanwhile the mystery keeps moving. It is "melting and penetrating" the deep, hidden "chthonic recesses of space." That word, chthonic, usually points to the underworld, so space becomes something buried and dark rather than open and bright. The verbs are physical, even a little unsettling, as if the universe were something to be dissolved and pierced.
The speaker seems more like an observer than a participant, watching with awe and a touch of unease. The mood is cosmic, restless, and slightly eerie. The poem suggests that the biggest mysteries may be unable to understand themselves, even as they spread across everything.