“JAMES BUCHANAN, “JOHN Y. MASON, “PIERRE SOULÉ. “Aix la Chapelle, October 18, 1854.” One brief sentence in the above describes the purport and substance of the whole document: “Our past history forbids that we should acquire the Island of Cuba without the consent of Spain, unless justified by the great law of self-preservation.” If the acquisition of the Island should become the very condition of our existence, then if Spain shall refuse to part with it for a price “far beyond its present value,” we shall be justified “in wresting it” from her, “upon the very same principle that would justify an individual in tearing down the burning house of his neighbor, if there were no other means of preventing the flames from destroying his own home.” This doctrine is not original with the Ostend conference, nor did it emanate from filibustering cupidity, nor is it a mere party issue. It has been as broadly asserted, and as confidently and ably advocated, by a Whig statesman and administration, as in the Ostend manifesto. Mr. Everett, United States Secretary of State, in his letter to the British and French ministers declining the alliance tendered by them to guarantee the possession of Cuba to Spain for all coming time, defends his refusal, on the ground that the United States have an interest in the condition of Cuba which may justify her in assuming dominion over it—an interest in comparison with which that of England and France dwindles into insignificance.