In the back of a manuscript collection of astronomical texts, which includes one of Abraham Ibn Ezra’s works on the use of the astrolabe (a tool for astronomical calculations), is a set of crude but generally accurate drawings of various parts of an astrolabe, glued into the codex. In a pinch, astrolabes could be constructed from paper, and it is conceivable that these were initially made for use but then pasted into the manuscript. This picture shows the back of the mater, or disk.