Metaphysics by Aristotle

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True knowledge is the knowledge of ultimate causes.

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There are four types of causes :

a.the formal cause -a plan or type ;

b.the final cause -a purpose ;

c.the material cause -matter,that which is used ; and

d.the efficient cause -that which initiates change.

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The study of being as being involves the attempt to discover first principles of explanation.

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The individual thing to which properties belong is the only true substance ;

substances are subjects,but never predicates.

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Since properties attach themselves to individuals of a certain kind,

the kind may also be called ''substance'' ;

thus,the essence of a thing is,in this sense,its substance.

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Matter is potentiality,the capacity to be something ;

matter is unlimited which is able to be limited by form;

when matter is limited by form,there is actuality.

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Forms,or universals,exist only in things.

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The process of change cannot go on to infinity ;

there must be an unmoved first mover which is eternal substance and actuality ;

such a first mover is good ;

it is divine thought thinking only of thought.

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