Issac Israeli, a medieval Jewish scholar of astronomy, completed his major work, Yesod ‘Olam , in Toledo, 1309/10 ce. The work has survived in over 50 manuscripts, with great textual variety, including intentional change. I discern two types of intentional change: (1) ‘proactive’, in which the motive for change is to improve the text; and (2) ‘reactive’, in which the motive for change is to cope with textual variants (caused by proactive changes). Preliminary to a stemma, I posit the following versions produced by proactive change: Version 1 – Alternate, with select sections substantially rewritten and streamlined; Version 2, regularly substituting streamlined current expression for Version 1’s more classical expression; Version 4, rephrasing to make the work more accessible to beginners, in addition to reactively mediating between Versions (1) and (2); and Version 3, attested in Ashkenaz, elucidating and intellectually contextualizing the received text.
Israel M. Sandman (Tue,) studied this question.