It will be a blessed day for the world when men are as willing to help each other as they are to assist Providence. The "London Cotton-Plant," a journal established to sustain the interests of Slavery in the Old World, is almost overpowered with acute distress for the Order of Creation, and offers its sustaining shoulder to the System of the Universe. "Fear nothing," it seems to say, "glorious structure of the Divine Architect! Giddings shall not touch you, nor shall Seward lay his sacrilegious hand on you!" "Who are ye?" murmurs the Voice, "that would reedit the works of the Almighty?" "Sublime, but misguided object of our compassion, we prefer to remain in the modest seclusion of namelessness, but we are published at Red-Lion Court, Fleet Street, and are sold for one shilling!" To judge from Mr. Cushing's letter, he has studied this organ of the sympathizers with the Pre-established Harmonies,--certainly there is a singular coincidence in the sentiments of both, so far as we can make them out. Both call themselves conservative, both are anti-philanthropists, both claim that public opinion is tending in the direction of their views, both affirm that their cause is that of the white man, and both appear to mean by white man the same thing,--the owner of a slave. But is not Mr. Cushing's anxiety misdirected, and wilfully so, in seeking the material for its forebodings of danger to the Union in the Free States? The only avowed disunionists of the North are the radical Abolitionists, whose position is the logical result of their admitting that under the Constitution it is impossible to touch Slavery where it exists, and who, therefore, seek in a dissolution of the federal compact an escape from complicity with what they believe an evil and a wrong,--with what, till within the last twenty years, was conceded to be such by the South itself. If Mr. Cushing be so great an admirer of stability in conviction, he might have found in these men the subject of something other than vituperation. There are men among them who might have won the foremost places of political advancement, could they have sacrificed their principles to their ambition, could they believe that public honors would heal as well as hide the wounds of self-respect. It is the South that advocates disunion, from sectional motives, and adds the spice of treason. The "London Cotton-Plant" says,--