The author reviews European and American ideas concerning the methods and purposes of political geography, and then applies these ideas to an analysis of the strategic position of Brazil. He identifies the South as the most vulnerable to attack from within the hemisphere; the Northeast most vulnerable to attack from outside. The challenge to Brazil, he writes, is to develop the interconnections within Brazil and to build its defenses so that it will never be necessary to accept military aid from outside. He quotes Washington as saying that any help one nation receives from another will have to be repaid later with a part of its independence.