By whatever causes produced, where such a centre of commerce exists, there always will be found a point of general interest to mankind,—­to all, at least, of those peoples who, whether directly commercial or not, share in the wide-spreading benefits and inconveniences arising from the fluctuations of trade.  But enterprising commercial countries are not content to be mere passive recipients of these diverse influences.  By the very characteristics which make them what they are, they are led perforce to desire, and to aim at, control of these decisive regions; for their tenure, like the key of a military position, exerts a vital effect upon the course of trade, and so upon the struggle, not only for bare existence, but for that increase of wealth, of prosperity, and of general consideration, which affect both the happiness and the dignity of nations.  Consequently, in every age, according to its particular temperament and circumstances, there will be found manifested this desire for control; sometimes latent in an attitude of simple watchfulness; sometimes starting into vivid action under the impulse of national jealousies, and issuing in diplomatic rivalries or hostile encounter.

Such, accordingly, has been the history of the Central American Isthmus since the time when it became recognized as the natural centre, towards which, if not thwarted by adverse influences, the current of intercourse between East and West inevitably must tend.  Here the direction of least resistance was indicated clearly by nature; and a concurrence of circumstances, partly inherent in the general character of the region, partly adventitious or accidental, contributed at an early date, and until very recently, to emphasize and enlarge the importance consequent upon the geographical situation and physical conformation of this narrow barrier between two great seas.  For centuries the West India Islands, circling the Caribbean, and guarding the exterior approaches to the Isthmus, continued to be the greatest single source of tropical products which had become increasingly necessary to the civilized nations of Europe.  In them, and in that portion of the continent which extended on either side of the Isthmus, known under the vague appellation of the Spanish Main, Great Britain, during her desperate strife with the first Napoleon,—­a strife for very existence,—­found the chief support of the commercial strength and credit that alone carried her to the triumphant end.  The Isthmus and the Caribbean were vital elements in determining the issue of that stern conflict.  For centuries, also, the treasures of Mexico and Peru, upon which depended the vigorous action of the great though decadent military kingdom of Spain, flowed towards and accumulated around the Isthmus, where they were reinforced by the tribute of the Philippine Islands, and whence they took their way in the lumbering galleons for the ports of the Peninsula.  Where factors of such decisive influence