Western art music distinguishes itself from the music of many other cultures by the use of polyphony. The need to show the simultaneous progression of two or more lines of music has generated a number of novel solutions over the millennium or so that Western musicians have practised polyphonic music. Monophony, of course, poses no particular problems of layout. Medieval scribes of monophonic music chose to write the music from left to right, borrowing the conventions from writing text, largely because monophony was texted. They inscribed the music either all the way across the page or in columns, but that choice did not materially affect the presentation of the music or its apprehension in reading or copying. The earliest practical sources for polyphony, the Winchester tropers of the early eleventh century, write the voices separately as monophony, in distinct sections of the book or even in two books.