It is interesting to note that the Aseret Hadibrot can be read according to Ta'am Elyon, in which the cantillations divide the Aseret Hadibrot into ten sentences, corresponding to God's Ten Declarations. They can also be read according to Ta'am Tachton, which has the effect of dividing the passage into thirteen sentences. In our printed Bibles, as a matter of fact, the Ten Declarations are read as thirteen sentences.

Why is this the case? If God expressed the Ten Declarations in ten sentences, why were they rearranged into thirteen?

I believe that the answer is the following: The validity and the motivation for the Commandments may rest on the fact that they represent the will of God. This is conveyed by reading that passage in the Torah in the precise way in which it was spoken, as ten sentences. Their validity and motivation may also rest on the cogency of the Commandments themselves, on the fact that they are compelling and convincing. In breaking up the Ten Declarations into thirteen verses, the Rabbis were conveying that an assessment of the Commandments themselves and a recognition of their inherent value - even aside from their being God-given - would convince the Jewish community to commit itself to them.

Both are excellent reasons, on this festival of Shavuot, to rededicate oneself to Torah.