The concept of property in Friedrich Ratzel's political geography. Friedrich Ratzel (1844-1904) worked out a geographical theory of state which he completed with a theory of property. Although the first was widely commented, his theory of property has never been the subject of any critical analysis. This might be a serious deficiency because, in Ratzel's view, the state cannot be separate from property, which, according to him, is the basic element of the state " internal composition ". In order to put this situation right, we will try to relate and analyse Ratzel's process that led to his theory of property.