Aristotle's Metaphysics E 2 and 3 are devoted to the discussion about accidental being and its causes, with the aim of assessing its credentials as a possible object of first philosophy. The result of this discussion is, in this sense, negative. However, first philosophy has something to say about accidental being, if only through a second order speech. The nature of the accidental is thus explored in these pages of Metaphysics, with the ultimate aim of confirming the impossibility of a scientific study (and a scientific discourse) about this way of being and its causes. The central part of this paper deals with E 2, 1026b27-1027a15, where Aristotle introduces the causes of accidental being. I endeavor to show that each of the three causes presented in these lines are compatible and relevant, as they can be understood, respectively, as the formal, efficient and material cause of what happens by accident.