[sometime lurker]

In defining an Article II “natural born Citizen,” it is important to find any authority from the Founding period who may inform us how the Founders and Framers themselves defined the clause.

I hate to post and run, but I'll make an exception today. From James Madison:

"It is an established maxim that birth is a criterion of allegiance. Birth however derives its force sometimes from place and sometimes from parentage, but in general place is the most certain criterion; it is what applies in the United States; it will therefore be unnecessary to investigate any other.

Note that James Madison is called "Father of the Constitution."

[ASA Vet]

Chief Justice Waite, in Minor v. Happersett, 88 U.S. 162 (1875), stated:

“The Constitution does not, in words, say who shall be natural-born citizens.
Resort must be had elsewhere to ascertain that.
At common-law, with the nomenclature of which the framers of the Constitution were familiar,
it was never doubted that all children born in a country of parents who were its citizens became themselves, upon their birth, citizens also.
These were natives, or natural-born citizens, as distinguished from aliens or foreigners.
Some authorities go further and include as citizens children born within the jurisdiction without reference to the citizenship of their parents.
As to this class there have been doubts, but never as to the first.”