  The Cartesian version of Anselm's traditional argument suggests that God has the intrinsic property of existence as part of a divine essence, in the same way a triangle has intrinsic properties such as having three internal angles summing to 180 degrees. Further, as with all divinely-held properties, God has that existence property as a perfection—that is, God exists in a perfect way, such that God cannot not exist. Gassendi rejects this reasoning on two grounds. First, we have no irrefutable intuitions of essences, whether such are supposed to be represented by properties of triangles or of God. Descartes' particular misstep here is to suggest that we may move from the definition of God (which we intuit as a clear and distinct notion) as essentially entailing the property of existence, to the view that there is such a thing as God with said property. A definition of a thing as having such and such properties does not commit us to the thing existing with those properties, even if one of those properties is said to be existence. This much was noted in Gaunilo's early criticism of Anselm's version. Yet the more general point Gassendi makes is that no intuitions untested by sensory experience will yield knowledge of God's essence or anything else, as the primary mode of attaining knowledge (and that by which any intuitions must be tested) is empirical demonstration. Second, presaging the Kantian criticism, existence is neither a perfection nor any sort of property or predicate of things that exist. Rather, existence is simply an aspect of things that exist, the mode or state of being that describes its existing. Existence is accordingly a precondition for bearing perfections (and for perfections being borne by the thing), rather than something which itself can be a perfection. If we refer to a thing's existence, we are only referring to a fact about the thing, that it exists. Rejecting the ontological argument, then, eliminates a sort of conceptual confusion: although we might think of perfections existing (in a thing), it is hard to conceive of what it would mean for existence to exist (in a thing), or for that matter, to not exist. Along similar lines, there is no reason to accept the underlying claim of the ontological argument that things which do not exist are either imperfect or lacking in any way (O III (DM) 379b-380b; R 490-6).