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Sorry guys.
I just don't buy the 'it has no significance' argument. Whilst I accept that often in stories things happen which are not important, in the case of the Torah, very little is wasted. Every line has some meaning, every action is significant.
My Rabbi says that the first five are relating to man's dealings with God, the second five relate to man's dealings with man.
"Ah, but" I hear you say, "What about the fifth Commandment, to honour your parents. That isn't to do with God, it's to do with man. So surely there should have been four Commandments on the first tablet, and six on the second"
Not so, says Rabbi Walach (a great Rabbi, of much learning). Your parents are your living link backwards through human history, all the way to creation. They are your link with God.
So, there we have it. Problem solved.