One need not be a chamber to be haunted

One need not be a chamber to be haunted,
One need not be a house;
The brain has corridors surpassing
Material place.

Far safer, of a midnight meeting
External ghost,
Than an interior confronting
That whiter host.

Far safer through an Abbey gallop,
The stones achase,
Than, moonless, one's own self encounter
In lonesome place.

Ourself, behind ourself concealed,
Should startle most;
Assassin, hid in our apartment,
Be horror's least.

The prudent carries a revolver,
He bolts the door,
O'erlooking a superior spectre
More near.