codex unicus is an insane concept. it means this text survived in a single copy, a single manuscript. any other copies went lost, were destroyed, were scraped clean, burned, rotted, or, in the most fabled and most comforting option, are still hidden somewhere in a cellar, in an archive, in a private collection never accessed before. do you want to check if a word really is an error? you can't. you want to confront a sentence with the one in another copy? you can't. you want to find out what the illegible ††† part means? you can't. it's lost. unknown. because the manuscript only exists in single copy, and we are so lucky we even have that.