THE MAYA CALENDAR
The Maya Calendar did not predict the end of time, but it did chart, with mathematical precision, the past, present and the future. Using their astute powers of observation, they plotted the stars, planets, and the passage of time, the Maya measured, not just linear time, but also the cycles of life and death.
It has stood the test of time, as to its accuracy over our current units of measure, all without atomic clocks, computers, and the telescope.