Since, among things which are, some are always in the same state and are of necessity (not necessity in the sense of compulsion but that which we assert of things because they cannot be otherwise), and some are not of necessity nor always, but for the most part, this is the principle and this the cause of the existence of the accidental; for that which is neither always nor for the most part, we call accidental.
Eta diren guztien artetik, hain zuzen ere, batzuk beti berdin eta nahitaez ematen direnez-"nahitaez", ez "indarrez" esaten den zentzuan, 30) "ezin bestelakoa izan" esaten dugun zentzuan baizik-, eta beste batzuk ez nahitaez, ezta beti berdin ematen ez direnez ere-gehienetan baizik-, hauxe da printzipioa eta hauxe da kausa akzidentearen izateaz.