I would like to know what "Like an unwritten piece of paper" means in the following sentences:
It did me good, this walk. It reminded me of the aimless ones I would take in Wrocław, when I could no longer stand being in the same space as Granny or at school. There was nowhere I could be without being with others, having to interact or to act. Even on my walks around the block, neighbours greeted and appraised. There were times when I’d get on the tram and ride across the city. I would get off at the last stop, in a neighbourhood where no one knew me, and I’d wander, not thinking, looking at the unknown streets and houses and people and feeling free and anonymous. Like an unwritten piece of paper. I’d forgotten the pleasure of this, and then and there, by the river, with the fields stretching out before me and the camp far behind me, something of that freedom returned. The water was clear and at the bottom I could see the bed of pebbles and light-brown mud and small fish swimming to and fro.
In this novel which is set in the 1980's in Poland under the socialist regime, where homosexuality was socially unacceptable, the protagonist Ludwik (a university graduate) left Poland in 1981 to live in the United States of America. And he remembers what it was like back then in Poland, where he went to the agricultural camp (which was mandatory for college graduation). At the camp, he took a walk after the field work was over, and felt anonymous like "an unwritten piece of paper."
In this part, I wonder what "unwritten" means here. Does it literally mean that the paper sheet was blank, with no letters written on it? Or does it perhaps mean that, though some letters were written on the paper, the name of the person who wrote those letters was not written on it, imparting the air of anonymous freedom...?
I am an English learner from South Korea, so thank you for your patience in advance as I may not know obvious things. I would very much appreciate your help. :)