Professor Cairnes begins judiciously by showing that in the beginning it was believed, not without very apparent cause, in England, that our war 'sprang from narrow and selfish views of sectional interests,' in which the free-trading South was in the right, and that the abolition of slavery was a mere pretence by which the North sought, without a color of truth, to attract foreign sympathy. And when we remember for how long a time slaves were returned by Federal officers to their owners, and how persistently anything like abolition, or even the most moderate emancipation, was earnestly and practically disowned by the Federal power, it is not wonderful, as Mr. Cairnes declares, that England should have regarded our claim to be fighting for the cause of free labor as a shallow deceit. Even as we write, we have before us a journal containing an allusion to an officer who attempted to return to slavery a contraband who had brought to him information of the greatest importance. Yet, despite the frightful appearances against us, our writer saw, through all, the truth, and declared that, as regarded the popular British abuse of this country, 'never was an explanation of a political catastrophe propounded, in more daring defiance of all the great and cardinal realities of the case with which it professed to deal.' Slavery is the cause and core of our national difficulty. Secession and Southern Rights have flourished in strength in exact ratio to the number of slaves in the States--nay, in the very counties in which slaves abounded. Slavery early developed a sectional class of politicians devoted to one object, who, by the sheer force of intense, unscrupulous application, from the year 1819 down to 1860, swayed our councils, gave an infamous character to American diplomacy, and stained our national character. They are called the Free Trade Party: why was it, then, that they never employed their power to accomplish that object, 'or how does it happen that, having submitted to the tariffs of 1832, 1842, and 1846, it should have resorted to the extreme measure of secession while under the tariff of 1857--a comparatively Free Trade law'? 'From 1842 down to 1860, the tendency of Federal legislation was distinctly in the direction of Free Trade.' 'If Free Trade was their main object, why did the Southern senators withdraw from their posts precisely at the time when their presence was most required to secure their cherished principle?' Or why did they not apply to their supple and infamous tool, Buchanan, to veto the bill? _Because they wished it to pass_--to make political capital against the North in England; and they accordingly aided its passage, Mr. Toombs being in the Senate, and actually voting for it! Or if it was a Free Trade question, why was it that the Western States did not take part with them?