1. The definition of quantity.—2. The exposition of quantity, what it is.—3. How line, superficies, and solid, are exposed.—4. How time is exposed.—5. How number is exposed.—6. How velocity is exposed.—7. How weight is exposed.—8. How the proportion of magnitudes is exposed.—9. How the proportion of times and velocities is exposed. [Sidenote: Definition of quantity.] 1. What and how manifold _dimension_ is, has been said in the 8th chapter, namely, that there are three dimensions, line or length, superficies, and solid; every one of which, if it be determined, that is, if the limits of it be made known, is commonly called _quantity_; for by _quantity_ all men understand that which is signified by that word, by which answer is made to the question, _How much is it?_ Whensoever, therefore, it is asked, for example, _How long is the journey?_ it is not answered indefinitely, _length_; nor, when it is asked, _How big is the field?_ is it answered indefinitely, _superficies_; nor, if a man ask, _How great is the bulk?_ indefinitely, _solid_: but it is answered determinately, the journey is a hundred miles; the field is a hundred acres; the bulk is a hundred cubical feet; or at least in some such manner, that the magnitude of the thing enquired after may by certain limits be comprehended in the mind. QUANTITY, therefore, cannot otherwise be defined, than to be _a dimension determined_, or _a dimension, whose limits are set out, either by their place, or by some comparison_. [Sidenote: The exposition of quantity, what it is.]