John, The most important invention is the Indo-Arab counting system with 0,1,2,3,4,5,6,7,8,9 with its positional information content (so 111 means one hundred plus one ten plus one unit), zero symbol, and operator property that by adding a zero to the righthand end of a string multiplies the number by the base value of 10. This system of counting and enumeration is completely universal and lies at the foundation of all quantitative science, economics, and mathematics.