Adding again a single line and double line to the trigrams then produces the 16 tetragrams. These 16 tetragrams represent the 16 fractals or fractions of light reflected on the moon by the sun. This becomes the universal application of Ifa's 16 signs. The ancients in nearly every culture used lunar calendars first. The lunar calendar reflected 29 1/2 days as seen by the earth in the southern hemisphere. There were 32 actual rotations. The full moon was the epitome of power and some cultures began the cycle at the full moon. From there, the moon would make its descent through the waning moon to the new moon. Then the ascent through the waxing moon crescent to return to the full. So, the 16 is related to the full moon and or the number of days it takes from the dark moon to the full moon. 15 are visible and the 16th is not. Other ways it has been presented is through the 16 phases of the moon. Here we can relate the odus
What is universal are all of the instances these same principles are reflected throughout the indigenous world. Not only do the 16 mother odus show up in West African traditions including the Yoruba, Dahomey, Igbo, Fon, Ewe, etc, they show up all over the world including the Americas and Indus Valley civilizations.
In Ifa, we express these principles this way as a multiplied or concentrated energy as vertical lines with the open lines being a double line and the closed line being a single row of lines.