 By contrast absolute necessity reigns in the heavenly spheres, Therefore, Avempace reckons three kinds of necessity: absolute, “by design”, and material. Interestingly, Avempace turns now to the lunar eclipses: they happen with absolute necessity in a determined period of time (IB-BA: 82). As he goes on and discusses possibility, Avempace admits possibility in relation to the eclipses, but combined with necessity—he literally says that “possibility shares necessity”. Possibility is present insofar as no specific limits determine the periods of time in which the eclipse exists potentially from those in which it exists actually. Necessity shows when it does not exist in a given time because of opposed motions caused by opposed unmoved movers.