what does his room represent to paul?

For a brief moment his room is the one place where he can feel that nothing has changed.

"I want to think myself back into that time. It is still in the room, I feel it at once, the walls have preserved it. My hands rest on the arms of the sofa; now I make myself at home and draw up my legs so that I sit comfortably in the corner, in the arms of the sofa. The little window is open, through it I see the familiar picture of the street with the rising spire of the church at the end. There are a couple of flowers on the table. Pen-holders, a shell as a paper-weight, the ink-well--here nothing is changed."