continued to live a quiet life in Amsterdam and then the Hague, grinding lenses for a living, and writing. He died of phthisis, probably caused by glass particles.
In the Ethica (published posthumously), he attempted to delineate a complete philosophical system using a Euclidean axiom-theorem schema of development. He said, "I shall consider human actions and appetites just as if I were considering lines, planes, and bodies." Definitions guided by axioms constitute the first step; the axioms are largely laws of logic, such as excluded middle and self-contradiction, or rationalist assumptions, like "Reality is rational."
Using this formulation, Spinoza accepted as ultimately real only the self-caused, self-existent, self-determined, self-temporalized: the Universe alone meets these criteria, and that one Reality can be conceived, and so, exists. He further identifies it as God and Substance.
Everything else is either a) a subdivided essence of the basic Substance (an attribute), or b) a subdivided modification (a mode) caused by some prior event.
Reality is both Extended and Thinking: both Mind and Matter are attributes of God-Substance-Reality-Universe. God is the full extent of the physical universe and the full intent of the psychic world; God is both Creator and Creation: "God's existence and His essence are equivalent." "Whether we think of Nature under the attribute of Extension or under the attribute of Thought or under any other attribute whatever, we shall discover one and the same order, or one and the same conneciton of causes."
This "doubleness" of manifestations is present in everything.
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