In the autumn of 1952 Borel, and his new wife Gaby (as she was always known) set off for the United States. Borel had been invited to spend a year at the Institute for Advanced Study at Princeton and this was extended to a second year. Haefliger writes:
Sa taglagas ng 1952 Borel, at ang kanyang bagong asawa Gaby (bilang siya ay palaging kilala) magpasabog para sa Pilipinas. Borel had inanyayahan sa gastusin sa isang taon at ang Institute for Advanced Study sa Princeton at ito ay pinalawig sa isang pangalawang taon. Haefliger magsusulat: