The Witches

The witches in Macbeth might seem very familiar to many of you.  They might remind you of many things in your life, such as the faits from the Disney movie, Hercules.

    The concept that our fate is controlled by beings is very common in Indo-european cultures.  In the hindi culture, the gods Rta in the vedas control the fates of people.  In Europe, this figure is often taken in the form of three evil witches.  This includes the greek Moirai, the northern germanic norns, the germanic Matres and Matrones, the slavic Boba Yoga, and the greek Moirai.  In these cultures, witches generally work in groups of 13, but these groups of three are the most common interculturaly, and all have the same purpose in culture.  Shakespeare was drawing from this continuity in culture to give meaning the the three witches that he would not have to explain to his audiences (this same thing was done by Lloyd Alexander in The Black Cauldron).  This means that the fates of Hercules are the same as Macbeth's witches, as they are the Moirai.
    Another continuity in cultures I found was that Christianity is ruled by the Holy Trinity - The father, the son, and the holy spirit.  Does this draw from these same historical continuity? I am not exactly sure, as I have not studied the middle eastern cultures, from which the monotheistic religions like Christianity come, but if anybody does know, does this rule of three apply here too? What about in America and Africa?  I wonder how far back this rule of three goes, please leave your knowledge in the comments!
    I also wonder if this has anything to do with the strength of the triangle.  The triangle has long been known to be the strongest of the figures, and is an engineering shape used throughout the history of man: ancient nomadic structures resembled triangles, all pyramids use triangle, et cetera.  I feel this is what our american fore-fathers also drew upon to create a stable government, as the three branches form a stable triangle of checks and balances.  Did ancient cultures put our fates in the hands of three people for this reason?

PS: When the when in Act I, Scene III of Macbeth, when the second witch says "I'll give thee a wind,"Shakespeare is directly referring to the witch from the Moirai known as Clotho, or The Spinner, as she spins and winds peoples lives, which was the Greeks' explanation of why nobody could have an all around perfect life.