circulation to the level of prices.

     There was soon great concern with ways and means of 
speeding up arithmetical calculations:

          It is hard for us to realize how laborious and slow 
     were the means at the disposal of medieval Europeans for 
     dealing with calculations ‘which seem to us of the 
     simplest character’. The introduction of Arabic numbers 
     into Europe provided more easily manipulated counters 
     than the Roman numbers, and the use of Arabic numbers 
     seems to have spread rapidly towards the end of the 
     sixteenth century, at least on the Continent. Between 
     about 1590 and 1617 John Napier invented his curious 
     ‘bones’ for calculating. He followed this invention with his 
     more celebrated discovery of logarithms. This was widely