The speaker is thinking of someone absent, and that longing sends them leaning over a patch of still water. Instead of a face they know, they see only "this head," a strangely detached way of describing their own reflection. It suggests how far the sadness has pulled them out of themselves, so that they look at their own body as if it belonged to someone else.
Then the poem widens. The earth keeps turning, yet the sky "has no motion," as though time has stopped for the speaker while the world carries on. The final image is small and exact: eyelashes loosen and fall into the water, where they meet their reflections "for the first and last time." That line holds a brief meeting and a permanent loss at once. The mood is quiet, hushed and heavy, a sorrow so still that even a falling eyelash feels like an event. The poem never says what happened, and the silence makes the feeling stronger.