This may be summed up as follows:--Defining the Mediterranean climate only by its rainfall, we may say that it prevails over lands both to the north and south of that sea, and these have all or most of their rainfall in winter, when the winds, though typically westerly, are often stormy and rendered variable by local conditions. In the summer there may be no rain at all, or, to the north, small amounts. To the north the region passes gradually into that colder zone where rain occurs abundantly both in summer and winter, while to the east and south the rainfall diminishes greatly, and there is a gradual transition to desert conditions. To the west the boundary of the region is theoretically the ocean, but the western coastline owes to its peculiar position a more abundant precipitation, which makes the vegetation of, _e. g._, Portugal present quite a different appearance from that of southern Italy or Algiers. These peculiarities of rainfall the region owes to its position between two great wind systems, of which one gains the mastery in winter and the other in summer. So far in this discussion we have spoken only of the distribution of the rainfall throughout the year, but there are other features of the Mediterranean climate which are almost as important in considering the effects of the climate on the life of the region. These are the amount of the rainfall, and the temperature. Beginning with general points, it is very important to notice that the rainfall throughout the area as a whole is relatively scanty, except where special conditions, _e. g._ great elevation, or local rain-bringing winds, increase it. Translated into terms of plant life this means that continuous forests of the type so characteristic of the greater part of Europe till man interfered, are relatively rare within the limits of the Mediterranean region. Looking at the same fact from the human standpoint we may say that the rainfall is often so scanty that irrigation is necessary before man can prosper. These two facts, that Mediterranean man had not to clear forests before he planted and sowed, as the Teutons were obliged to do, and that he had often to bring water artificially before his crops would grow, have been of supreme importance in the evolution of Mediterranean civilisation. Even at this stage it is interesting to note that France in this, as in many other respects, has shared in two civilisations, for her territory to the south shows Mediterranean characters, and elsewhere resembles the cool temperate zone of Europe.