English law was their law, the law they grew up with. For over a year after the American Revolution started they still regarded themselves as Englishmen, Englishmen standing up for their rights as Englishmen against an unjust government. English law was not some foreign law imposed on them. My opinion is that they used Blackstone, because he was a formerly fellow countryman writing about English law, as I've said, the actual law that the British subjects who transformed themselves into American citizens were used to using. The law they used to buy their house, to sell the food they produced in their fields. That whole legal tradition was not thrown away on July 4, 1776, the allegiance to the King and the unity with the Kingdom of Great Britain was.
Natural born is a legal term of art. Something that has a specific meaning in the law. if they had wished to specify that the American President had to be born on American soil to parents who were American citizens, they could have done so in so many words. They already very carefully crafted that passage to allow one specific man to run for the Presidency(Alexander Hamilton) should he wish to do so, so the words were not casually chosen.
The whole point of being able to write the law is to write the law that you think proper. If you fail to write the law clearly, the law as written must be interpreted as broadly as possible. If you fail to specify that American born in America to parents who are not Americans are barred from the Presidency, you should not be surprised when the Constitution is interpreted against your wishes. And that assumes they did in fact want to discriminate against Americans not born to American parents, something I do not believe.
I already know what your opinion is, I guess we're just going to have to disagree. With two incompatible references if it comes to that, the Supreme Court will have to make a ruling. I suspect they will choose the Englishman over the foreigner, who was not part of the English legal tradition. But that's just my prediction, I could be wrong.
I must say though, that in all the decades I have been an American I have never heard that passage interpreted any other way but: if you are born in America you are eligible for the Presidency, if you are a naturalized American you are not. Until this Presidential cycle. Now suddenly that is not good enough. I can understand why some people who had the same decades-long experience I had might think this all smacks of being poor losers. Think carefully about how happy you would be to see this suddenly "whipped out" to disqualify Sarah Palin if it was her life story that she was born in America to non-American parents.