The tradition of Roger Bacon's Opus maius has many confusing aspects. No single MS contains all parts of the work, and several parts are transmitted separately, out of their original context and in different versions. Several reasons can be given for this confusion. One reason is that Bacon himself incorporated the same material into different projects and on each occasion adjusted the material to its new environment. Similarly, as he informs us, the text of the Opus maius itself was the outcome of several drafts. Another reason is the sheer bulk of the Opus maius. When Bacon sent it off to the pope he had to divide it into four separate volumes.