 However, Taurellus challenges the assumption that active and passive properties of natural things should be regarded as contraries. This is why: “Nothing takes on its contrary but rather cedes when the contrary comes; but passivity increases with the increase of activity” (PT: 284). Hence, his argument against the contrary nature of active and passive properties is that an increase of passive power is compatible with an increase of active power. But if activity and passivity are not contraries, “they are present in the same subject and proceed from the same cause” (PT: 292). At the same time, Taurellus holds on to the assumption that the active properties of things have to be explained by the existence of an active principle. This is why he does not eliminate the notion of form from his ontology. On the contrary, because active and passive properties are not contraries, he believes that they proceed from forms alone: 