It comes from a then contemporary legal reference on international law. It is disputed only by those who want to dispute it. It means strictly that the parentage (both) are citizens of the nation from which the child can claim citizenship. Where the birth occurs is not relevant to this requirement. In general, one can claim U.S. citizenship wherever born as long as one of the parents is a U.S. citizen. But that would not be "natural born." Your birth citizenship is "natural" if it derives from both parents who are already citizens. (I have a cousin born in France of a U.S. mother, and she has both U.S. and French citizenship.) The purpose is indeed as you describe.
It comes from a then contemporary legal reference on international law. It is disputed only by those who want to dispute it. It means strictly that the parentage (both) are citizens of the nation from which the child can claim citizenship. Where the birth occurs is not relevant to this requirement. In general, one can claim U.S. citizenship wherever born as long as one of the parents is a U.S. citizen. But that would not be "natural born." Your birth citizenship is "natural" if it derives from both parents who are already citizens. (I have a cousin born in France of a U.S. mother, and she has both U.S. and French citizenship.) The purpose is indeed as you describe.