That which the painter designates by the expressions “Swiss scenery” or “Italian sky” is based on a vague feeling of the local natural character. The azure of the sky, the effects of light and shade, the haze floating on the distant horizon, the forms of animals, the succulence of plants, the bright glossy surface of the leaves, the outlines of mountains, all combine to produce the elements on which depends the impression of any one region. It must be admitted, however, that in all latitudes the same kind of rocks, as trachyte, basalt, porphyritic schist, and dolomite, form mountain groups of exactly similar physiognomy. Thus the greenstone cliffs of South America and Mexico resemble those of the Fichtel mountains of Germany, in like manner as among animals, the form of the Allco, or the original canine race of the New Continent, is analogous to that of the European race. The inorganic crust of the earth is as it were independent of climatic influences; perhaps, because diversity of climate arising from difference of latitude is of more recent date than the formations of the earth, or that the hardening crust, in solidifying and discharging its caloric, acquired its temperature from internal and not from external causes[80]. All formations are, therefore, common to every quarter of the globe and assume the like forms. Everywhere basalt rises in twin mountains and truncated cones; everywhere trap-porphyry presents itself to the eye under the form of grotesquely-shaped masses of rock, while granite terminates in gently rounded summits. Thus, too, similar vegetable forms, as pines and oaks, alike crown the mountain declivities of Sweden and those of the most southern portion of Mexico[81]. But notwithstanding all this coincidence of form, and resemblance of the outlines of individual portions, the grouping of the mass, as a whole, presents the greatest diversity of character.