This chapter begins with a strong distinction between spoken number words and number symbols. Basically the number concept is the recognition of a single entity combined with the understanding that another can be added to it, another then added to that aggregate, another to that, and so on. Different cultures make different use of the counting facility; some generate lots of number words and a very few generate almost none. Different words can be used because the number symbol does not represent the sound of the number word; it represents the concept behind the word. Some historians of Western mathematics have even attributed Western progress in arithmetic and calculation to the advent of base 10 positional system. The concept of zero is important in itself, but it is crucial to any base positional system. The main cord, pendant cords, spaces between cords, color differences, and knots and knot clusters are all visible in the photograph.