EM dash, Dickinson

When trying to interpret what the dashes mean in Dickinson’s poem it is important to remember that the way Dickinson used them might be entirely different from the way the reader might perceive it. Of course the more obvious interpretation of the dashes could to be to connect and/or to separate ideas, but the problem is that we as readers have no way to know how Dickinson intended us to perceive it. In other words, the readers have no way to know how Dickinson used them, and we as readers all have different ways of understanding or reading it.
Another way in which we as readers could interpret the meaning of the dashes is that the dashes may be trying to put an emphasis or certain words or phrases. If this is true in anyway, it once again brings up the issue on what exactly is Dickinson trying to get across to the readers and that will be entirely different to every reader.
In my personal opinion it seems that the dashes try to make an emphasis on certain words and phrases by connecting them. For example when she says

“Of Chambers as the Cedars—Impregnable of Eye—"

She is trying to emphasis the strength and durability of the “Chambers as the Cedars” by stating that it is “Impregnable of Eye”. Cedars are known for resisting damaging insects such as termites which are very abundant on the east coast and in the south. Cedar is also known for having a very pleasant scent so it was used in higher society because it is more expensive. So having a chamber built out of cedar would be a very optimal choice, and Dickinson is trying to put emphasis on this chamber by using the dashes to make sure the reader connect the two phases.