Ten is the basic social group, from which the idea of the minyan developed. There are a number of decads and pentads of laws in the Torah, which itself has five books, half of ten. The Psalmist gives ten synonyms for mitzvah in Psalm 119.
Not all the ten in the Decalogue are laws in the usual sense of the word. The first one does not explicitly order us to do anything, and it cannot be adjudicated in a court of law. But it identifies the lawgiver, God who redeemed the people from bondage. Maimonides sees it as a command to the mind – “Know that there is a First Cause bringing all else into existence” – not a command to believe, since no-one can force a person to believe when they do not want to.
Another opinion said it was a command to accept God’s sovereignty: “The Monarch whose great deeds on your behalf you witnessed and experienced, that is the Monarch to whom you must be loyal and whose commands you must obey.”
The problem disappears, however, when we note that the Torah itself calls the Decalogue Aseret HaDib’rot, “Ten Words” or “Ten Statements” – i.e. ten principles. The English term Decalogue conveys a similar idea since it comes from the Greek for Ten Words.
Christianity, wishing to maintain the idea of ten laws, saw “I am the Lord your God” as merely a preamble. The Greek and Protestant Churches divide our second “commandment” into two, separating the law against polytheism and the law against idolatry. The Roman Catholics and Lutherans divide the law against coveting into two.
That law against coveting is still a problem in that no earthly court can read your mind and punish you for being envious. If the Decalogue is seen as a set of principles and not laws, this becomes a warning against fighting the facts. An illustration is given by Abraham Ibn Ezra. He says that one peasant can covet the good fortune of a second, more prosperous peasant. But he is not likely to covet the king’s daughter because he knows he could not have her except in a fantasy world.
A believer knows what has been allocated to him has been decided by God and whilst he can be ambitious he has no right to covet the impossible, like the peasant marrying the princess.
If “Do not covet” is seen as a law, it shows us that it is in the heavenly court that we will be held accountable for our infractions. Certain precepts are also actionable on earth, especially killing and stealing, but that does not detract from the status of the document as a set of moral obligations to God.
The rabbis point out that though coveting takes place in the human heart and mind, it can lead to the infringement of the other precepts. If you strongly covet something that is your neighbour’s you can find yourself telling lies in order to acquire it (an infringement of “Do not bear false witness”), stealing it (“Do not steal”), even taking your neighbour’s wife (“Do not commit adultery”), and even murdering your neighbour (“Do not kill”).