 According to Kunugiyama, the cover art chosen from one of Saint-Exupéry's watercolour illustrations contained the planets Saturn and Jupiter, plus the star Aldebaran, arranged as an isosceles triangle, a celestial configuration which occurred in the early 1940s, and which he likely knew would next reoccur in the year 2000.Saint-Exupéry possessed superior mathematical skills and was a master celestial navigator, a vocation he had studied at Salon-de-Provence with the "Armée de l'Air" (French Air Force).Stacy Schiff, one of Saint-Exupéry's principal biographers, wrote of him and his most famous work, "rarely have an author and a character been so intimately bound together as Antoine de Saint-Exupéry and his Little Prince", and remarking of their dual fates, "the two remain tangled together, twin innocents who fell from the sky".