<P> The natural borders of France (French: Frontières naturelles de la France) are a political and geographic theory developed in France, notably during the French Revolution . They correspond to the Rhine, the Atlantic Ocean and Mediterranean Sea, the Pyrenees and the Alps, according to the revolutionaries . </P> <P> Most historians of France today reject the theory of France's natural borders . According to University of California, Berkeley, historian Peter Sahlins, "as a model of French identity, it formed part of a constitutive myth of the state ." </P> <P> The first mention of the natural borders appeared in 1642 in an apocryphal statement by Cardinal Richelieu . Even so, it was not until 1786 when the idea was again developed . The Prussian Jean - Baptiste Cloots published that year the Wishes of a Gallophile (French: Vœux d'un gallophile) and pronounced himself in favor of the annexation by France of the left bank of the Rhine, "natural boundary of the Gauls" (French: borne naturelle des Gaules). This notion was influential among the French revolutionaries after 1790, notably among the Jacobins . After the victory of Valmy on September 20, 1792, the National Convention urged the soldiers to go after the Prussian armies of the other bank of the Rhine . For General Adam Philippe de Custine, commander of the Army of the Rhine, "if the Rhine is not the limit of the Republic, it will perish" (Si le Rhin n'est pas la limite de la République, elle périra). On December 17, the Convention adopted the Declaration of the French Revolutionary Administration of Conquered Lands (French: Décret sur l'administration révolutionnaire française des pays conquis), prelude to the annexation of Wallonia by France . This was demanded by Georges Jacques Danton on January 21, 1793, justifying that "the limits of France are marked by nature, we will reach the four corners of the horizon, to the edge of the Rhine, to the edge of the ocean, to the edge of the Pyrenees, to the edge of the Alps . The boundaries of our Republic must be there ." </P>

Mention the cardinal idea of the french revolution