 This role of matter can be contrasted to the causal role of the three further types of causes—of form, of efficient  cause, and of final cause respectively. This is so, because, as Aristotle adds, form and final cause often coincide. Moreover, when a nature is  specified as a first efficient cause, cause and effect are the same in  form (or in species), though this is not to say that one and the same  entity causes itself and is caused through its own causal efficacy (Physics 2.7, 198a24–27, cf. Metaphysics 8.4, 1044a32–b1).