Cf. I, Chapp. LXVII (with notes), LXXXV.
The contingent, sumbebêkos, is that which is, but might not be (Aristotle, Physics, VIII, v). The term is still of interest to the logician, and to the psychologist, who concerns himself with the freedom of the will, but has lost all interest in physical science, except in the cognate sense of accidental.
Of God and His Creatures: 3.72