We know that the Celtic people now living in Brittany, Devonshire, Cornwall, Wales, Scotland, and Ireland, though now considerably mixed, are the descendants of the old Celtic inhabitants of France and Britain. But there is a great deal of unwritten history for which we may look in vain to the ordinary sources of information, such as books, and which is only to be read in quite different records,--in antiquities buried up in peat-beds, in bogs, in ruins and ancient forts, or camps; and last but not least, in the names of places, rivers, or mountains. The hills, the valleys, the rivers, are the only writing-tablets on which unlettered nations have been able to inscribe their annals. For this kind of history we must go to the antiquary, and, above all, to the philologist, who tells us the meaning of the names of places, and who the people were who gave the names that we see on our maps. The great advances which have of late years been made in our knowledge of the primeval races of men, or at least of nations but little known in the annals of history, are largely due to the interpretation of the obscure records preserved in local names. The Celtic, the Iberian, the Teutonic, the Scandinavian, and Sclavonic races have thus for the most part made known to us their migrations, conquests, and defeats. And so by studying the names of places, rivers, and hills, as well as by careful collection of works of art, implements, coins, such as may be seen in many a museum, it has been possible to read a great deal of early history which would otherwise have been lost. Those who have studied these matters say they can trace wave after wave of population which has thus left its mark,--Gaelic, Cymric (or Welsh), Saxon, Anglian, Norwegian, Danish, Norman, and Flemish. Thus it can be proved from the names on the map that almost the whole of England was once Celtic, whereas now the Celts are almost entirely confined to the hills. The Peak of Derbyshire and the mountains of Cumberland retain a greater number of Celtic names than the districts surrounding them; and the hills of Devonshire long served as a barrier to protect the Celts of Cornwall from Anglo-Saxon conquerors.