Spinoza defined God as "a substance consisting of infinite attributes, each of which expresses eternal and infinite essence", and since "no cause or reason" can prevent such a being from existing, it therefore must exist. This is a form of the ontological argument, which is claimed to prove the existence of God, but Spinoza went further in stating that it showed that only God exists. Accordingly, he stated that "Whatever is, is in God, and nothing can exist or be conceived without God". However, this God is abstract and impersonal. Spinoza viewed God and Nature as two names for the same reality, namely a single, fundamental substance (meaning "that which stands beneath" rather than "matter") that is the basis of the universe and of which all lesser "entities" are actually modes or modifications. This ""Deus sive Natura"" ('God or Nature') is a being of infinitely many attributes, of which thought and extension are two, with the former being the sphere of ideas and the latter that of physical objects. His account of the nature of reality then seems to treat the physical and mental worlds as intertwined, causally related, and deriving from the same Substance.