Simon Stevin quotes

The Rule of Three, or Golden Rule of Arithmeticall whole Numbers. Be the three termes given 2 3 4. ...To finde their fourth proporcionall Terme: that is to say, in such Reason to the third terme 4, as the second terme 3, is to the first terme 2 [Modern notation: \frac{x}{4} = \frac{3}{2}]. ...Multiply the second terme 3, by the third terme 4, & giveth the product 12: which dividing by the first terme 2, giveth the Quotient 6: I say that 6 is the fourth proportional terme required. (Simon Stevin)
The sixt Definition. A Whole number is either a unitie, or a compounded multitude of unities.
Simon Stevin
...the use of the Disme ...to teach such as doe not already know the use and practize of Numeration, and the foure principles of common Arithmetick, in whole numbers, namely, Addition, Substraction, Multiplication, & Division, together with the Golden Rule, sufficient to instruct the most ignorant in the usuall practize of this Art of Disme or Decimall Arithmeticke.
Simon Stevin
The second Definition. Number is that which expresseth the quantitie of each thing.
Simon Stevin
The seventh Definition. The Golden Rule, or Rule of three, is that by which to three tearmes given, the fourth proportionall tearme is found.
Simon Stevin
The first Part. Of the Definitions of the Dismes. The first Definition. Disme is a kind of Arithmeticke, invented by the tenth progression, consisting in Characters of Cyphers; whereby a certaine number is described, and by which also all accounts which happen in humane affayres, are dispatched by whole numbers, without fractions or broken numbers.
Simon Stevin
Multiplication of whole Numbers ...Note, that for the more easie solution of this proposition, it were necessary to have in memory the multiplication of the 9 simple Characters among themselves, learning them by rote out of the Table here placed...
Simon Stevin
[The books of Euclid pass on to us] something admirable and very necessary to see and to read, namely the order in the method of writing on mathematics in that aforementioned time of the wise age.
Simon Stevin
If all this be not put in practize... it wil be beneficiall to our successors, if future men shal hereafter be of such nature as our predecessors, who were never negligent of so great advantage. ...they may all deliver them selves when they will, from so much and so great labour.
Simon Stevin
Our intention in this Disme is to worke all by whole numbers: for seing that in any affayres, men reckon not of the thousandth part of a mite, grayne, &c. as the like is also used of the principall Geometricians, and Astronomers, in computacions of great consequence, as Ptolome & Johannes Monta-regio have not described their Tables of Arches, Chords, or Sines, in extreme perfection (as possibly they might have done by Multinomiall numbers,) because that imperfection (considering the scope and end of those Tables) is more convenient then such perfection.
Simon Stevin