CHAPTER IX. OCEANS AND ENCLOSED SEAS

The water a factor in man's mobility--Oceans and seas the factor of union in universal history--Origin of navigation--Primitive forms--Relation of river to marine navigation--Retarded and advanced navigation--Geographic conditions in Polynesia--Mediterranean versus Atlantic seamanship--Three geographic stages of maritime development--Enclosed seas as areas of ethnic and cultural assimilation--Assimilation facilitated by ethnic kinship--Importance of zonal and continental location of enclosed seas--Thalassic character of the Indian Ocean--Limitations of small area in enclosed seas--Successive maritime periods in history--Contrasted historical rôles of northern and southern hemispheres--Size of the ocean--Neutrality of the seas--_Mare clausum and Mare liberum_.