Part 1: God


  1. Self—caused means something of which:
    • the essence involves existence, or
    • the nature is only conceivable as existent.
  2. A thing is finite after its kind, when it can be limited by another thing of the same nature.
    • For instance, a body is finite because we always conceive another greater body.
    • So a thought is limited by another thought, but a body is not limited by thought, nor a thought limited by a body.
  3. Substance is something in itself and conceived through itself.
    • In other words, something of which a conception can be formed independently of any other conception.
  4. Attribute is something which the intellect perceives as constituting the essence of substance.
  5. Mode are the modifications of substance, or that which exists in, and is conceived through, something other than itself.
  6. God means a being absolutely infinite.
    • It is a substance consisting in infinite attributes, of which each expresses eternal and infinite essentiality.
    • I say absolutely infinite, not infinite after its kind, for infinite attributes may be denied for a thing infinite only after its kind.
    • But something absolutely infinite contains in its essence whatever expresses reality and involves no negation.
  7. A free thing is something:
    • that exists solely by the necessity of its own nature
    • that does actions which are determined by itself alone.

On the other hand, a thing is necessary, or rather constrained, if it is determined by something external to itself, to a fixed and definite method of existence or action.


  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, an effect necessarily follows.
    • On the other hand, if there is no definite cause, 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.


Proposition 1: Substance is by nature prior to its modifications.

Proposition 2: Two substances, whose attributes are different, have nothing in common.

Proposition 3:Things which have nothing in common cannot be one the cause of the other.

Proposition 4.Two or more distinct things are distinguished one from the other, either by the difference of the attributes of the substances, or by the difference of their modifications. Proof: Everything which exists, exists either in itself or in something else (Axiom 1).

Proposition 5There cannot exist in the universe two or more substances having the same nature or attribute. Proof: If several distinct substances be granted, they must be distinguished one from the other, either by the difference of their attributes, or by the difference of their modifications (Prop. 4).

Proposition 6: One substance cannot be produced by another substance. Proof: It is impossible for two substances to have an identical attribute (Prop. 2).

Corollary: It follows that a substance cannot be produced by anything external to itself.

Proposition 7:Existence belongs to the nature of substances.

Proof: Substance cannot be produced by anything external (Corollary, Prop 6).

Proposition 8:Every substance is necessarily infinite. Proof: There can only be one substance with an identical attribute, and existence follows from its nature (Prop. 7). Note 1: Finite existence involves a partial negation. Note 2: It will be difficult for those who think about things loosely, and have not been accustomed to know them by their primary causes, to comprehend the demonstration of Prop. 7. 2. No definition implies or expresses a certain number of individuals, inasmuch as it expresses nothing beyond the nature of the thing defined. 3. There is necessarily for each individual existent thing a cause why it should exist. 4. This cause of existence must either be contained in the nature and definition of the thing defined, or must be postulated apart from such definition.