A person stands alone in a garden and does something slightly absurd: they give an order to the light, asking it to turn into herrings and arrive "in good time." The odd request is the heart of the poem. The title, "Schooling," helps explain it. Herrings travel in schools, so the speaker pictures light moving like a flickering, silvery shoal of fish, which is a good match for how sunlight glints and shifts. The word also hints at teaching, as if the speaker is half-seriously trying to train the light.
The garden is called "of little hopes," and that phrase sets the feeling. The speaker isn't despairing, but their wishes are small and tender, the kind you hardly dare say aloud. Talking to the light is both playful and a little lonely. The mood is quiet, wistful and gently humorous. The final line, "in good time," adds patience: the speaker doesn't demand anything quickly, only hopes that something good will eventually come.