Thomas Hobbes (1588–1679). Of Man, Being the First Part of Leviathan.
The Harvard Classics. 1909–14.

Chapter IX

Of the Several Subjects of Knowledge

THERE are of ‘knowledge’ two kinds, whereof one is ‘knowledge of fact,’ the other ‘knowledge of the consequence of one affirmation to another.’ The former is nothing else but sense and memory, and is ‘absolute knowledge,’ as when we see a fact doing or remember it done; and this is the knowledge required in a witness. The latter is called ‘science,’ and is ‘conditional,’ as when we know that ‘if the figure shown be a circle, then any straight line through the centre shall divide it into two equal parts.’ And this is the knowledge required in a philosopher, that is to say of him that pretends to reasoning.

The register of ‘knowledge of fact’ is called ‘history,’ whereof there be two sorts: one called ‘natural history,’ which is the history of such facts or effects of Nature as have no dependence on man’s ‘will,’ such as are the histories of ‘metals,’ ‘plants,’ ‘animals,’ ‘regions,’ and the like. The other is ‘civil history,’ which is the history of the voluntary actions of men in commonwealths.

The registers of science are such ‘books,’ as contain the ‘demonstrations’ of consequences of one affirmation to another, and are commonly called ‘books of philosophy,’ whereof the sorts are many, according to the diversity of the matter, and may be divided in such manner as I have divided them in the following table (pp. 360–361).