The Duodecimal System

Otherwise generally in the case of those Italian measures, which were not connected with Greek standards and were probably developed by the Italians before they came into contact with the Greeks, there prevailed the partition of the "whole" (-as-) into twelve "units" (-unciae-). The very earliest Latin priesthoods, the colleges of the Salii and Arvales,(5) as well as the leagues of the Etruscan cities, were organized on the basis of the number twelve. The same number predominated in the Roman system of weights and in the measures of length, where the pound (-libra-) and the foot (-pes-) were usually subdivided into twelve parts; the unit of the Roman measures of surface was the "driving" (-actus-) of 120 square feet, a combination of the decimal and duodecimal systems.(6) Similar arrangements as to the measures of capacity may have passed into oblivion.
If we inquire into the basis of the duodecimal system and consider how it can have happened that, in addition to ten, twelve should have been so early and universally singled out from the equal series of numbers, we shall probably be able to find no other source to which it can be referred than a comparison of the solar and lunar periods. Still more than the double hand of ten fingers did the solar cycle of nearly twelve lunar periods first suggest to man the profound conception of an unit composed of equal units, and thereby originate the idea of a system of numbers, the first step towards mathematical thought. The consistent duodecimal development of this idea appears to have belonged to the Italian nation, and to have preceded the first contact with the Greeks.
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