Thousands of years ago in China, the Lo River flooded, inundating the local population. The people were desperate, and frantically made offerings and sacrifices to the river god, asking him to return the water to its banks.

Suddenly a turtle surfaced on the river. The people saw that there was a pattern on its shell, a grid of nine squares. Each square had dots adding up to numbers. No matter which way the dots were added across the rows either diagonally, vertically, or horizontally, the sum was 15. The diagram was called the “Lo Shu,” or “Lo River Writing.”

The turtle gave the people the pattern on its back as a map or grid of the natural flow of chi and the elements, and this square with its numbers became a foundational tool in Feng Shui and Taoist traditions. The square is also carried as an amulet or placed in homes and offices as a protective charm.

The turtle that emerged from the river had an unusual 3 x 3 pattern on its shell which later became the basis of the Lo Shu Square, a mathematical grid where the sum of numbers from each row, column or diagonal is the same.

Basically, no matter which direction you add the numbers—horizontal, vertical or diagonal—they always add up to 15. Number 15 is considered a powerful number because it corresponds to the number of days in each of the 24 cycles of Chinese solar year. In other words, it is the number of days in the cycle of the new moon to the full moon.