Spain may be naturally divided into four main parts. The first is Andalusia, which is formed by the Sierra Morena, which separates the valley of the Baetis (Guadalquivir) from that of the Guadiana. This part is a compact country by itself, being separated from Murcia by the heights in the east. The second part is bounded on the south by the range of Orospeda, and in the north by that of Idubeda, which extends in an eastern direction towards the sea. These mountains separate the river basins of the Tago and Douro from that of the Ebro, and run at a right angle with the Sierra Morena. This division comprises the greater part of Valencia, Aragon, and Catalonia, that is, the whole river basin of the Ebro. The third division consists of the mountainous countries of Galicia, Asturias, and Cantabria. The fourth, lastly, consists of the river basin of the Tago. These divisions are so completely founded on the natural features of the country, that throughout the history of Spain they appear with perfect distinctness, and hence they may also be taken as a guide in ancient history. Andalusia, the southernmost part, is almost identical with ancient _Baetica_, and, as is observed even by Strabo, is a country quite different from the rest of Spain. It has indeed many points of resemblance with Valencia, but is at the same time essentially different from it: it is in fact a country of a superior character. While Valencia is flat, and well watered, but wanting in energy, Andalusia and Granada are countries matured by the sun in the highest degree; they are scarcely European, but almost like tropical countries. The eastern division, or the country of the Iberus, if we examine its northern parts, Aragon and Catalonia, already greatly resembles a northern country. Valencia stands in the middle between them. The whole of the northern division is a mighty mountainous country; the mountains in Asturia and Biscay are very high, though they do not reach the snow line; the highest parts are in the neighbourhood of the sources of the Douro. The country of the Tago is throughout a table-land, very high at its commencement, piercingly cold and unhealthy as far as the frontier of Portugal, and almost without any mountains; at the commencement alone we have the ranges separating Old and New Castile. Between the Sierra Morena and the Douro, we have the large plain of Estremadura, which is fertile but unhealthy, and perfectly flat; the plain of Leon is scarcely inhabitable on account of its drought and barrenness; the southern parts of Castile are productive, and the continuation of the valley into Portugal changes its character so much as to become extremely rich; it still contains large plains, but the greater part is a beautiful hilly country.