  According to Rees, the Instauratio Magna comprises two branches: (1) Bacon's famous scientific method, and (2) his semi-Paracelsian world system as “a vast, comprehensive system of speculative physics” (Rees 1986, 418). For (2) Bacon conjoins his specific version of Paracelsian cosmic chemistry to Islamic celestial kinematics (especially in Alpetragius [al-Bitruji]; see Zinner 1988, 71). The chemical world system is used to support Bacon's explanation of celestial motion in the face of contemporary astronomical problems (Rees 1975b, 161f.). There are thus two sections in Bacon's Instauratio, which imply the modes of their own explanation.