SPREAD OF UNDERSTANDING 11 



presence, just as Monsieur Jourdain spoke in prose, without his 

 knowing it. 



The most convincing proof of Stevin's genius was perhaps that 

 after having explained the decimal fractions, he did not rest there. 

 He saw at once the logical consequences of their introduction and 

 the immense possibilities which were involved. Decimal numbers 

 are naturally introduced when we enumerate objects if we count 

 them by tens, but what will happen if our numbers are the result 

 not of a direct enumeration, but of a mensuration — as when we 

 want to know the length of a piece of cloth or the weight of a 

 cheese? Then it is clear that we can only obtain the same fractions 

 that are included in our instruments. Thus if we deal with feet and 

 inches or shillings and pence we are driven to use duodecimal 

 fractions which do not at all tally with our decimal system. Stevin 

 was the first to realize that the adoption of a decimal system of 

 numbers led irresistibly to that of a decimal system of weights 

 and measures (and vice versa) and that neither adoption was 

 truly complete without the other. To measure according to one 

 system and to count according to another destroyed the economy 

 of both. 



This great vision of Stevin's was beautifully simple, as simple as 

 it was deep, yet it was not embodied until the end of the eighteenth 

 century, when the French Revolution created the so-called metric 

 system. The idea was accepted by the Assemblee Constituante in 

 1790 and the system became legally established in France. During 

 the last century it spread all over the world, except, strangely 

 enough, in the Anglo-Saxon countries where it met — and still 

 meets — with a resistance, which is the stronger in that it is irra- 

 tional. In the fifteenth century, there were still any number of 

 learned doctors and professors who claimed that the Roman let- 

 ters were much clearer than the Hindu numerals. Was it not much 

 simpler to write CCCXLVIII than 348? In the same way, there 

 are still many English and American apostles, full of learning, who 

 will prove to everybody who will listen that their incongruous sets 

 of weights, measures and moneys are much more convenient than 



