I was just thinking about how can the Torah be eternal, like the Tanakh says, and yet have changing iterations (eg Abraham – if you want to count that, then the Sinai covenant, then alterations ready for the land in Deuteronomy, and then the change in emphasis brought in by Yeshua), and the best analogy I have come up with is that the same God who gave Torah is the same God who made our bones. Our bones always stay in the same position and perform the same function, but when our lifestyle changes, the bones will totally rebuild themselves to fit the circumstances. So if you go from a sedentary lifestyle or job to something not so sedentary your bones will quickly change shape to fit the new circumstances. Torah is just like that. This is why Yeshua can uphold the law (see Matthew 5) and yet alter some parts of the practice of it, and the early church followed in his footsteps with the adjustments they made to deal with fellowship and eating with Gentiles who had come to faith in Yeshua. Think about it, and I think you will like the analogy….