Benedict (Baruch) Spinoza (1632-1677) was the son of a Jewish merchant from Amsterdam. His father and grandfather were originally Spanish crypto-Jews -- that is, Jews who were forced to adopt Christianity in post-Islamic Spain, but secretly remained Jewish. He was educated in traditional Jewish Curriculum. His father died when he was 21, after which he was embroiled in a lawsuit with his stepsister over his father's estate. Spinoza won the suit, but nevertheless handed virtually all of it over to his stepsister. Shortly after, Spinoza's budding theological speculations prompted conflict with Jewish leaders. Spinoza publicly contended that the scriptures do not maintain that God has no body, that angels exist, or that the soul is immortal. After failed attempts to silence him, he was excommunicated in 1656. For a time Spinoza was associated with a former Jesuit who ran a school for children. Spinoza used this as an opportunity to further his own education and to supplement his income by teaching in the school. At this time he also learned the trade of lens grinding for glasses and telescopes.

In his late twenties, he supervised a discussion group on philosophical and theological issues. As his own ideas developed, he went on retreat from Amsterdam for three years to formulate them in writing. At a cottage in Rijnsburg, he wrote A Short Treatise on God, Man and his Well-Being, and On the Improvement of the Understanding. He also composed a geometric version of Descartes' Principles of Philosophy, which friends encouraged him to publish. Part of the purpose of the work was to pave the way for publishing his own thoughts which were critical of Cartesianism. By producing such a work, he could not be accused later of not understanding Descartes. The work appeared in 1663 and was the only writing of Spinoza's published with his name on it during his life. Further developing his own ideas, over the next two years Spinoza composed his greatest work, The Ethics. In 1663 Spinoza left Rijnsburg and moved near The Hague. Hoping to publish the Ethics, and anticipating controversy, he wrote and published anonymously his Tractatus Thologico-Politicus (1670) which defends the liberty to philosophize in the face of religious or political interference. After a self- initiated and failed diplomatic mission to France, Spinoza and he was forced to give up hopes of publishing the Ethics. He died in 1677 from a lung disease, the result of breathing dust from lens grinding.

In Part One of the Ethics, "Concerning God," after presenting a short list of definitions and axioms, Spinoza deduces 36 propositions which explain the nature of God. The most important of these is Proposition 14, which expresses Spinoza's pantheism: "Besides God, no substance can be granted or conceived." The term "pantheism" (literally all-God) means that God is identical to the universe as a whole. For example my car, my house, and even I myself are all parts of God. Other Western philosophers before Spinoza advocated pantheism, including Xenophanes, Parmenides, Plotinus, and Meister Eckhardt. However, the vast majority of Western philosophers and theologians strongly rejected this view in favor of a transcendent concept of God which holds that God is distinct from his creation. Indeed, some theologians maintained that God has the attribute of separateness thus being completely separate from the rest of the universe, including the physical world and humans. Spinoza's argument for pantheism in Proposition 14 is as follows:

Proposition 5. There cannot exist in the universe two or more substances having the same nature or attribute.
Proposition 11: God (defined as a substance consisting of infinite attributes, of which each expresses eternal and infinite essentiality) necessarily exists.
Therefore, Proposition 14: Besides God, no substance can be granted or conceived.

As noted, Spinoza opens part one of the Ethics with a list of definitions and axioms. His list of definitions are as follows:

1. By that which is self-caused, I mean that of which the essence involves existence, or that of which the nature is only conceivable as existent.
2. A thing is called finite after its kind, when it can be limited by another thing of the same nature; for instance, a body is called finite because we always conceive another greater body. So, also, a thought is limited by another thought, but a body is not limited by thought, nor a thought by body.
3. By substance, I mean that which is in itself, and is conceived through itself: in other words, that of which a conception can be formed independently of any other conception.
4. By attribute, I mean that which the intellect perceives as constituting the essence of substance.
5. By mode, I mean the modifications of substance, or that which exists in, and is conceived through, something other than itself.
6. By God, I mean a being absolutely infinite -- that is, a substance consisting in infinite attributes, of which each expresses eternal and infinite essentiality. ...
7. That thing is called free, which exists solely by the necessity of its own nature, and of which the action is determined by itself alone. On the other hand, that thing is necessary, or rather constrained, which is determined by something external to itself to a fixed and definite method of existence or action.
8. By eternity, I mean existence itself, in so far as it is conceived necessarily to follow solely from the definition of that which is eternal.

Like definitions, axioms are also foundational elements from which propositions are derived. Rather than defining key terms, though, Spinoza's axioms stipulate some foundational fact about the world.

1. Everything which exists, exists either in itself or in something else.
2. That which cannot be conceived through anything else must be conceived through itself.
3. From a given definite cause and effect necessarily follows; and, on the other hand, if no definite cause be granted, it is impossible that an effect can follow.
4. The knowledge of an effect depends on and involves the knowledge of a cause.
5. Things which have nothing in common cannot be understood, the one by means of the other; the conception of one does not involve the conception of the other.
6. A true idea must correspond with its ideate or object.
7. If a thing can be conceived as non-existing, its essence does not involve existence.

1. (a) The idea of God is that of substance with infinite attributes, each of which is eternally and infinitely essential (Def. 6)
2. (b) Suppose that God does not exist
3. (c) Then existence is not part of his essence
4. (d) However, existence belongs to the nature of a substance
5. (e) Therefore, God exists

Having proved that (a) no two substances can have the same attributes (Proposition 5), and (b) God exists with infinite attributes (Proposition 11), Spinoza proceeds to conclude that God is the only substance (Proposition 14). Again, The proof for this is as follows:

1. (a) There cannot exist in the universe two or more substances having the same nature or attribute (Proposition 5)
2. (b) God (defined as a substance consisting of infinite attributes, of which each expresses eternal and infinite essentiality) necessarily exists (Proposition 11)
3. (c) Therefore, besides God, no substance can be granted or conceived (Proposition 14).

• Corollary I -- Clearly, therefore: 1. God is one, that is (by Def. vi.) only one substance can be granted in the universe, and that substance is absolutely infinite, as we have already indicated (in the note to Prop. x.).
• Corollary II. -- It follows: 2. That extension and thought are either attributes of God or (by Ax. i.) accidents (affectiones) of the attributes of God.
• Prop. XV. Whatsoever is, is in God, and without God nothing can be, or be conceived.

If all things are part of God, then the three-dimensional universe itself is part of God. This means that, in some sense, God has a body. However, Spinoza criticizes those who anthropomorphize the nature of God's body by maintaining that it is finite, and even susceptible to having emotions (given the fact that human emotions are the result of a human body). Spinoza harshly rejects both of these limitations on God's physical nature. However, the vast majority of western philosophers reject the notion that God has a three-dimensional body of any sort. He presents two traditional criticisms of the view that God has a body. First, there are absurdities involved when we consider quantity to be infinite. For example, one foot has twelve times the infinite number of points that one inch does. Second. God is active, and divided matter is passive. The two are thus incompatible. In response, Spinoza argues that the key error in all of these arguments is the assumption that extended substance is composed of parts. Instead, he maintains that the notion of extended substance must be drawn from the more foundational notion of infinite quality, and infinite quality cannot be measured.

In the remainder of Part I of the Ethics, Spinoza derives various properties of God. He summarizes these properties in the opening paragraph of the Appendix to Part I.

Appendix. In the foregoing I have explained the nature and properties of God. I have shown that (1) he necessarily exists, (2) that he is one, (3) that he is, and acts solely by the necessity of his own nature, (4) that he is the free cause of all things, and how he is so, (5) that all things are in God, and so depend on him, that without him they could neither exist nor be conceived, and (6) that all things are predetermined by God, not through his free will or absolute fiat, but from the very nature of God or infinite power. I have further, where occasion offered, taken caret to remove the prejudices which might impede the comprehension of my demonstrations. Yet there still remain misconceptions, not a few which might and may prove very grave hindrances to the understanding of the ordering of things, as I have explained it above. I have therefore thought it worth while to bring these misconceptions before the bar of reason.