In no characteristic is existing society in the West so sharply distinguished from the earlier societies, whether of Europe or the East, than in its conception of time. To the ancient Chinese or Greek, to the Arab herdsman or Mexican peon of today, time is represented by the cyclic processes of nature, the alternation of day and night, the passage from season to season. The nomads and farmers measured and still measure their day from sunrise to sunset, and their year in terms of seedtime and harvest, of the falling leaf and the ice thawing on the lakes and rivers. The farmer worked according to the elements, the craftsman for as long as he felt it necessary to perfect his product. Time was seen as a process of natural change, and men were not concerned in its exact measurement. For this reason civilizations highly developed in other respects had the most primitive means of measuring time: the hour glass with its trickling sand or dripping water, the sun dial, useless on a dull day, and the candle or lamp whose unburnt remnant of oil or wax indicated the hours. All these devices were approximate and inexact, and were often rendered unreliable by the weather or the personal laziness of the tender. Nowhere in the ancient or mediaeval world were more than a tiny minority of men concerned with time in the terms of mathematical exactitude.