 It is worth noting that Averroes’ own account of causal necessity in nature is roughly in accord with Avicenna’s. As discussed above (in  §3.1),  Avicenna holds that “with the existence of its cause, the existence of the effect is necessary”. He also holds, however, that the existence of a sublunary substance, which functions as a cause, is, typically, not sufficient for the exercise of its causality and, thus, typically, not sufficient for the existence of the effect of its causality. For example, fire functions as a cause of the burning of cotton only when its power to burn is actualized in the cotton. This not only requires that contact between agent (fire) and patient (cotton) be unimpeded but also that the patient (cotton) is itself in a suitable state, e.g., the cotton is not wet.