In many ways Spinoza is the first Aspect Dualist. His theory that God is everything and everything is God breaks down into a Substance Monism. The terms God, Nature and Substance are equivalent for Spinoza. However he thought both mind and matter were different modes of the same Substance.

It has thus been argued that he was a Pantheist, however Spinoza's God is an abstract concept with no anthropomorphic or sentient features.