Leonhard Euler · 1770 (1828 English ed.) · Internet Archive
Elements of Algebra
All 627 leaves · leaf 38
Transcription
ELEMENTS
OF
ALGEBRA.
PART I.
Containing the Analysis of Determinate Quantities.
SECTION I.
Of the different Methods of calculating Simple Quantities.
CHAP. I.
Of Mathematics in general.
ARTICLE I:
WHATEVER is capable of increase or diminution, is called *magnitude*, or *quantity*.
A sum of money therefore is a quantity, since we may increase it or diminish it. It is the same with a weight, and other things of this nature.
2. From this definition, it is evident, that the different kinds of magnitude must be so various, as to render it difficult to enumerate them: and this is the origin of the different branches of the Mathematics, each being employed on a particular kind of magnitude. Mathematics, in general, is the *science of quantity*; or, the science which investigates the means of measuring quantity.
3. Now, we cannot measure or determine any quantity, except by considering some other quantity of the same kind as known, and pointing out their mutual relation. If it were proposed, for example, to determine the quantity of a sum of money, we should take some known piece of money,
B
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