[Everyone perceives pieces of art in different ways depending upon each individual's experiences: this is only my interpretation.]
of material things to the threat of the workings of our minds and/or hearts.
One reviewer observes:
To Dickinson, mental disability is a real and very threatening reality, although we do not know if or to what extent she personally encountered it.
It may simply be, as is often the case with Dickinson, that she is observing this phenomenon, in herself or in someone else.
Regardless, the first stanza presents the main idea that reflects the title, for a brain is much like a house with its own haunted corridors.
The second stanza relates the relative ease one may approach a real ghost as opposed to the "Cooler host," the mind that haunts us with ideas, memories, worries, etc.
My interpretation of the third stanza is that it would be easier to gallop on a horse through an abbey (which is a holy place, like a monastery or convent) with stones chasing one, than meet up with yourself or your soul, and confronting it without weapons to defend you.
The "stones a'chase" could be interpreted one of two ways, as I see it. First, if the abbey is old and falling down, as they were built of stone, if the building were falling to ruin (perhaps a more logical circumstance when one might find himself on a horse within such a place), then the galloping might dislodge old stones, or they might be falling anyway and the speed of the horse would aid the rider in avoiding injury from those stones.
However, if one were within the abbey courtyard and was being attacked (one can only imagine why this would be the case), the stones may be missiles, weapons thrown at the rider, which he tries to avoid.
The only reason I might assume that the stones are being used as weapons is the third line's reference to "Unarmed, one's a'self encounter / In lonesome Place." However, the use of "unarmed" may have nothing to do with the stones, but may stand alone with the sense that there is no weapon that can defend us from our ideas, especially when things are most upsetting—when we are alone.
The fourth stanza tells us that it is worse to be taken by surprise by our thoughts, than by an assassin hidden within our home. The fifth stanza ties into that same thought: a physical body has a means of defense: take out a gun, lock the door; but with the mind, "a superior spectre" (ghost, apparition) that would be, once again, our thoughts, our ideas, our fears, etc.
It is difficult for me to be certain of Dickinson's use of apostrophes in "a'chase" and "a'self encounter." In the second and the fourth line of the third stanza, the author may be trying to add a syllable to provide the same number of beats in the lines' rhythm. The same may be the case for the first and third line as well. (There does seem to be a pattern in the second, third and fourth stanzas, where the second and fourth lines of each have two beats.)
I hope this is of some help.