Although Spinoza’s system had very strong theological elements and he was motivated to construct it for the ethical purpose of determining how to live, he did not base morality on God, but rather on adequate human knowledge. Such knowledge would enable both an ability to control the passions and live peacefully with others. However, indirectly, this knowledge of nature amounted to knowledge of God because, according to Spinoza, God was present throughout nature.

Spinoza wrote philosophy in the form of geometrical proofs and began with axioms from which he proved his conclusions. First, he made the assumption that substance exists. Substance, he continued, has infinite attributes, but humans can perceive only two of these: extension and thought (or matter and mind).

Spinoza’s metaphysics was a monism. Only one thing existed and that was God. God, according to Spinoza, was “a being absolutely infinite.” Although God had infinite attributes, each one of which expressed His nature without limitation to itself, humans can perceive or understand only two of God’s infinite attributes: thought and material bodies, or extension. Each attribute has both infinite modes and finite modes, although finite modes are infinite in number. A person, for example, is one finite mode of God, existing in God as both a mode of thought and a mode of extension.

One way of understanding Spinoza is that mind and matter are different ways of viewing the same thing that exists in God. As everything that exists, God is nature, but nature is also God. Spinoza distinguished between natura naturans, or God in his active role as creating, and natural naturata, or what we humans perceive as nature.