If the sacred literature of Judaism and Christianity take weak hold upon the western mind, this is largely because it is written in the symbolism of the pastoral nomad.  Its figures of speech reflect life in deserts and grasslands.  For these figures the western mind has few or vague corresponding ideas.  It loses, therefore, half the import, for instance, of the Twenty-third Psalm, that picture of the nomad shepherd guiding his flock across parched and trackless plains, to bring them at evening, weary, hungry, thirsty, to the fresh pastures and waving palms of some oasis, whose green tints stand out in vivid contrast to the tawny wastes of the encompassing sands.  “He leadeth me beside the still waters,” not the noisy rushing stream of the rainy lands, but the quiet desert pool that reflects the stars.  What real significance has the tropical radiance of the lotus flower, the sacred symbol of Buddhism, for the Mongolian lama in the cold and arid borders of Gobi or the wind-swept highlands of sterile Tibet?  And yet these exotic ideas live on, even if they no longer bloom in the uncongenial soil.  But to explain them in terms of their present environment would be indeed impossible.

[Sidenote:  Partial response to environment]

A people may present at any given time only a partial response to their environment also for other reasons.  This may be either because their arrival has been too recent for the new habitat to make its influence felt; or because, even after long residence, one overpowering geographic factor has operated to the temporary exclusion of all others.  Under these circumstances, suddenly acquired geographic advantages of a high order or such advantages, long possessed but tardily made available by the release of national powers from more pressing tasks, may institute a new trend of historical development, resulting more from stimulating geographic conditions than from the natural capacities or aptitudes of the people themselves.  Such developments, though often brilliant, are likely to be short-lived and to end suddenly or disastrously, because not sustained by a deep-seated national impulse animating the whole mass of the people.  They cease when the first enthusiasm spends itself, or when outside competition is intensified, or the material rewards decrease.

[Sidenote:  The case of Spain.]

An illustration is found in the mediaeval history of Spain.  The intercontinental location of the Iberian Peninsula exposed it to the Saracen conquest and to the constant reinforcements to Islam power furnished by the Mohammedanized Berbers of North Africa.  For seven centuries this location was the dominant geographic factor in Spain’s history.  It made the expulsion of the Moors the sole object of all the Iberian states, converted the country into an armed camp, made the gentleman adventurer and Christian knight the national ideal.  It placed the center of political control high up on the barren plateau