A book in ancient times consisted of a single long strip of paper or parchment, which was usually kept rolled upon a stick, and was unrolled when a person wished to read it. The roll was usually written on one side only, and hence the particular notice of one that was "written within and without." (Ezekiel 2:10) The writing was arranged in columns.
Smith’s Bible Dictionary
Roll
Smith’s Bible Dictionary, William Smith (1863). Public domain, from the CrossWire SWORD module.