As association is the primal condition of progress, let us see how nature throws societies together or holds them asunder. In some directions there are greater facilities for intercommunication (another essential of improvement) than in other directions. Wherever man is most in harmony with nature, there he progresses most rapidly; wherever nature offers the greatest advantages, such as a sea that invites to commerce, an elevated plateau lifting its occupants above the malaria of a tropical lowland, a sheltering mountain range that wards off inclement winds and bars out hostile neighbors, there culture flourishes best.
OBJECTIVE AND SUBJECTIVE STIMULANTS.
So that humanity, in its twofold nature, is dependent for its development upon two distinct species of stimulants, objective and subjective. Material causations, or those forces which minister to the requirements of man's material nature but upon which his intellectual progress is dependent, are configurations of surface, soil, climate, and food. Those physical conditions which, when favorable, give to their possessors wealth and leisure, are the inevitable precursors of culture. Immaterial causations are those forces which act more directly upon man's immaterial nature, as association, religion, wealth, leisure, and government. Continuing the analysis, let us first examine physical stimulants. Admitting readily two of M. Taine's primordial humanity-moving forces, 'le milieu' or environment, and his 'le moment' or inherited impulse, we will pass over the third force 'la race';—for inherent differences in race, in the present stage of science, are purely hypothetical; it remains yet to be proved that one nation is primarily inherently inferior or superior to another nation. That man once created is moulded and modified by his environment, there can be no doubt. Even a cursory survey of the globe presents some indications favorable and unfavorable to the unfolding of the different forms of organic being.
Great continents, for instance, appear to be congenial to the development of animal life; islands and lesser continents to the growth of exuberant vegetation. Thus, in the eastern hemisphere, which is a compact oval, essentially continental, with vast areas far removed from the influence of the ocean, flourish the elephant, the hippopotamus, the rhinoceros, the courageous lion, the fierce tiger, the largest and lordliest of animal kind, while in the more oceanic western hemisphere inferior types prevail. Cold and dryness characterize the one; heat and humidity the other; in one are the greatest deserts, in the other the greatest lakes and rivers. Warm oceanic currents bathe the frosty shores of the northern extremities of the continents and render them habitable; the moisture-laden equatorial atmosphere clothes the adjacent islands and firm land in emerald verdure. Upon the same parallel of latitude are the great Sahara Desert of Africa, and the wilderness of luxuriant billowy foliage of the American Isthmus. In warm, moist climates, such species of animal life attain the fullest development as are dependent upon the aqueous and herbous agencies. In tropical America are seen the largest reptiles, the most gorgeous insects,—there the inhabitants of warm marshes and sluggish waters assume gigantic proportions, while only upon the broad inland prairies or upon elevated mountain ranges, away from the influences of warm waters and humid atmospheres, are found the buffalo, bear, and elk. The very complexion and temperament of man are affected by these vegetative and umbrageous elements. Unprotected from the perpendicular rays of the sun, the African is black, muscular, and cheerful; under the shadow of primeval forest, man assumes a coppery hue, lacking the endurance of the negro, and becomes in disposition cold and melancholy.
And again, if we look for the natural causes which tend to promote or retard association, we find in climates and continental configurations the chief agencies. The continent of the two Americas, in its greatest length, lies north and south, the eastern continental group extends east and west. Primitive people naturally would spread out in those directions which offered the least change of climate from that of the primitive centre. Obviously, variations of climate are greater in following a meridian than along a parallel of latitude. Thus, the tropical man passing along a meridian is driven back by unendurable cold, while a continent may be traversed on any parallel, elevations excepted, with but little variation in temperature. A savage, exposed and inexperienced, not knowing how to protect himself against severe changes of climate, could not travel far in a northerly or southerly direction without suffering severely from the cold or heat; hence, other things being equal, the inhabitants of a country whose greatest length lay east and west, would intermingle more readily than those whose territory extended north and south.
CLIMATE AND MOUNTAIN RANGES.
That the eastern hemisphere attained a higher degree of civilization than the western, may be partly due to the fact, that the former presents wider spaces of uniform climate than the latter. The climatic zones of the New World, besides being shorter, are intersected by mountain barriers, which tend to retard the intercourse that would otherwise naturally follow. Thus the Mexican table-land, the seat of Aztec civilization, is a tierra fria situated above the insalubrious tierra caliente of either coast and the healthful tierra templada of the slopes, but below the mountain ranges which rise from this table-land, forming a tierra frígida, a region of perpetual snow. To this day, the natives of the Mexican plateau cannot live on the sea-coast, though less than a day's journey distant.
Between the climatic zones which extend through Europe and Asia, there are contrasts as marked and changes as sudden, but these differences are between the different zones rather than between longitudinal sections of the same zone. Hence, in the old world, where climatic zones are separated by mountain ranges which make the transition from one to the other sudden and abrupt, we see a greater diversity of race than in America, where the natural barriers extend north and south and intersect the climatic zones, thereby bringing the inhabitants along a meridian in easier communication than those who live in the same latitude but who are separated by mountains, table-lands and large rivers. That is, if color and race are dependent on climate, America should offer greater varieties in color and race than Europe, for America traverses the most latitudes; but the mountain barriers of America extend north and south, thereby forcing its people to intermingle, if at all, in that direction, while the chief ranges of the eastern continent extend east and west, parallel with climatic zones, thereby forming in themselves distinctly marked lines between peoples, forcing the African to remain under his burning sun, and the northmen in their cooler latitudes; so that in the several climatic zones of the old world, we see the human race distinctly marked, Aryan, Semitic, and Turanian—white, black, and yellow—while throughout the two Americas, from Alaska to Tierra del Fuego, type and color are singularly uniform.
Who can picture the mighty tide of humanity, which, while the eastern hemisphere has been developing so high a state of culture, in America has ebbed and flowed between barbarisms and civilizations? Through what long and desperate struggles, continuing age after age through the lives of nations, now advancing, now receding, have these peoples passed? Asia, from its central position and favorable climate, would seem naturally to encourage a redundant population and a spontaneous civilization; the waters of the Mediterranean invite commerce and intercommunication of nations, while the British Isles, from their insular situation and distance from hypothetical primitive centres, would seem necessarily to remain longer in a state of barbarism. In the Pacific States of North America we find the densest population north along the shores of the ocean, and south on the cordillera table-land, from the fact that the former offers the best facilities for food and locomotion until the latter is reached, when the interior presents the most favorable dwelling-place for man.
Climate affects both mental and moral endowments, the temperament of the body, and the texture of the brain; physical energy, and mental vigor. Temperate climates are more conducive to civilization, not for the reason given by Mr Harris, "as developing the higher qualities, and not invigorating the baser feelings", for the Hyperborean is as unchaste and as great a slave to passion as the sub-equatorial man—but because a temperate climate, while it lures to exertion, rewards the laborer.