Held to their continents by bonds that often fail to bind, subjected by their outward-facing peripheral location to every centrifugal force, feeling only slightly the pull of the great central mass behind, peninsulas are often further detached economically and historically by their own contrasted local conditions.  A sharp transition in geological formation and therefore in soil, a difference of climate, rainfall, drainage system, of flora or fauna, serve greatly to emphasize the lack of community of interests with the continental interior, and therefore produce an inevitable diversity of historical development.[785] Hence, many peninsulas insulate their people as completely as islands.  It is hard to say whether the Pyrenean peninsula or Sicily, Scandinavia or Great Britain, has held itself more aloof from the political history of remaining Europe; whether Korea is not more entitled to its name of the Hermit Kingdom than island Japan could ever be; whether the Peloponnesus or Euboea was more intimately associated with the radiant life of ancient Hellas.  These questions lead to another, namely, whether a high mountain wall like the Pyrenees, or a narrow strait like that of Messina is the more effective geographical boundary.

[Sidenote:  Continental base a zone of transition.]

Peninsulas not infrequently gain in breadth as they approach the continent; here they tend to abate their distinctive character as lobes of the mainland, together with the ethnic and historical marks of isolation.  Here they form a doubtful boundary zone of mingled continental and peninsular development.  Such peninsulas fall naturally, therefore, into a continental and a peninsular section, and reveal this segmentation in the differentiated history of the two portions.  That great military geographer Napoleon distinguished the Italy of the Po basin as Italie continentale, and the Apennine section as Presqu’ile.  Not only is the former broader, but, expanding like a tree trunk near the ground, it sends its roots well back into the massive interior of the continent; it is dominated more by the Alps than by the Apennines; it contains a lowland and a river of continental proportions, for which there is no space on the long, narrow spur of southern Italy.  If its geographical character approximates that of the mainland, so does its ethnic and historical.  The Po basin is a well defined area of race characterization, in which influences have made for intermixture.  South of the crest of the Apennines the Italian language in its purity begins, in contrast to the Gallo-Italian of the north.  This mountain ridge has also held apart the dark, short dolichocephalic stock of the Mediterranean race from the fairer, taller, broad-headed Celts, who have moved down into the Po basin from the Alps, and the Germans and Illyrians who have entered it from the northeast.[786] Northern Italy is therefore allied ethnically, as it has often been united politically, to the neighboring countries abutting upon the Alps, so that it has experienced only in a partial degree that detachment which has stamped the history of the Apennine section.