in a state of controlled panic, a student of Blake
I would suggest that the reference to Blake indicates the nature of his poetry and the task of students. The task of students is to analyze the whys and wherefores of literary works through the meaning and form of all the whats. They approach the whats in awkward, student scholarship, being finicky over the assortment: literary technique, literary device, enjambment, allusion, rhetorical scheme, synecdoche ....The student's task is foreboding. Blake's poetry can be forbidding ... certainly philosophically.
So the little sandpiper runs steadily about the pursuit of his purpose, ever playing a game of tag, advancing and retreating, with the ocean's surf in the same manner with which students approach the difficult task of foraging intellectual nourishment from Blake's works: in a state of controlled (sandpipers and students must both control their dread of having nourishment wash away in the tide) panic (the emotional result of the realization of the daunting challenge at hand).
A Divine Image
Cruelty has a human heart,
And Jealousy a human face;
Terror the human form divine,
And Secresy the human dress.
The human dress is forged iron,
The human form a fiery forge,
The human face a furnace sealed,
The human heart its hungry gorge. (William Blake, looking forbidding)
The quoted phrase refers to the fear the bird feels as it runs alongside the noisy, crashing ocean, which regularly sends gushes of water in toward the bird. Many of us have seen this behavior by sandpipers-- the way they run along the edge of the beach but run away from the incoming waves, yet still continue to run along the beach. They fear the flood of water, but they control their panic enough to continue running alongside it, looking for sustenance.
The reference to Blake is much more obscure, and there seems to be no obvious critical consensus about its meaning. We often think of Blake, after all, as an extremely self-confident and assertive poet who seemed panicked by almost nothing. Why his students should seemed panicked is also very unclear. Some critics seem this phrase as a small jab at Blake, but they rarely explain the nature of the jab. In short, if you are puzzled by the reference to Blake, you are hardly the only person who seems confused and unsure. Perhaps this was part of the effect Bishop hoped to achieve.
This link may help a bit:
I'm thinking whether it's because in "auguries of Innocence' - William Blake, he also mentioned 'to see the world in a grain of sand' . Both of them are seeing details in the nature. The sandpiper might be personified to show that human beings are also often panic, neglecting the beauty of nature.
There's another question raised. What is the tone of 'Poor bird, he is obsessed'? Is that negative or positive?