In the poem "The Voice You hear..." by Thomas Lux, what does cathedral mean?

I think that the poet uses this word to invoke the idea
that your mind is a place that is both quiet and in some way holy or above the physical
world.

A real cathedral is a place where you go to be quiet
and to escape from the reality of the every day world.  The services in a cathedral and
the meditation you can do take you to a higher plane of
existence.

I think that the poet is saying that a similar
thing happens when you read.  When you read, you can retreat into a cathedral where you
are taken away from the physical realities and problems of your everyday life.  You are
instead transported to a different plane of existence.