It must be admitted that the full weight and power of the Ten Commandments is not only in their content, but in the special way they were given.
After all, the prohibitions against murder, theft, rape, and giving false witness are basic elements of the social contract; they are formal commitments necessary for a society to exist.
In the Ten Commandments, however, "Thou shalt not murder" is not a ruling set by some local chief or council to avoid vengeful blood feuds.
It is the command of an Almighty God, and this is what gives it power and meaning.
To transgress against any of the commands of the Torah is primarily to defy God, and only after that is it an offense against society.
This, however, is only a relatively external, formalistic aspect of the giving of the Torah.
More significant, it is an act from above to below, the crossing of the infinite gap between God and the world.
Whether one conceives the gap logically/philosophically, or whether it is felt in terms of the sublime, there is no way man can cross it.
One can only cry out in despair, "What has He to do with us dwellers of the dust?"
To be sure, this is not just a modern thought; it is repeated often enough in the Bible and is probably a basic experience in all religions.
Indeed, the inner message of the Ten Commandments is in answer to this feeling of man's insignificance.
It is a central aspect of the confrontation at Sinai, as it is written:
"Behold, the Lord our God has showed us His glory and His greatness, and we have heard His voice out of the midst of the fire: we have seen this day that God does talk with man, and He lives" (Deuteronomy 5:21).
The importance of this encounter is not in the actual words spoken but that God appeared before man and told him what to do, that God established some sort of contact with man.
And this is the meaning of the whole Torah; all the rest is commentary and expansion.
–Rabbi Adin Steinsaltz
From “The Giving and the Receiving of the Torah,” p. 86, by Rabbi Adin Steinsaltz