Underground

Each night he must
be carried through artificial tunnels and dream recurrent dreams.
Just as the ties recur beneath his train, these underlie
his rushing brain. He does not dare look out the window,
For the third rail, the unbroken draught of poison,
runs there beside him. He regards it as a disease
he has inherited the susceptibility to. He has to keep
his hands in his pockets, as others must wear mufflers.

                                                        from The Man Moth, by Elizabeth Bishop