Then the theatre was changed To something else. Its past was a souvenir (5-6)
At some point in modernity, something changed for human consciousness. At least Stevens says it did. He's not totally clear about what changed. But based on what he writes about in this poem, it must've been something big.
It has to be living, to learn the speech of the place. (7)
Modern minds aren't the same as minds in Shakespeare's time. If we're going to respond to poetry, then poetry's going to have to meet us halfway. It needs to change with the changing times and do what it has to if it wants people to stay interested. No more of this timeless stuff. We need poetry that changes, because people's minds change over time.
It has to face the men of the time and to meet The women of the time. (8-9)
In order to be relevant, poetry needs to crawl into the minds of men and women of a certain historical moment. It needs to figure out what their fears and desires are, and it needs to speak to those things if it's going to be meaningful for people.