It seems to us, then, highly important, in every possible view of the case, that the Federal Government should avail itself of the opportunity given it by the Southern rebellion to perform this act of justice to the negro race; to assimilate the labor system of the South to that of the North; to remove a great moral and political wrong; and to wipe out the foul stain of slavery, which has hitherto sullied the otherwise bright escutcheon of our Republic. We are no fanatics on the subject of slavery, as is well known to our readers, and we make no extraordinary pretensions to modern philanthropy; but we cannot help fearing that, if the government lets slip the present opportunity of doing justice to the negro race, and of placing our republic throughout in harmony with modern civilization, God, who is especially the God of the poor and the oppressed, will never give victory to our arms, or suffer us to succeed in our efforts to suppress rebellion and restore peace and integrity in the Union. THE NEW YORK HERALD ON THE WAR. With the secession of Virginia, there is going to be enacted on the banks of the Potomac one of the most terrible conflicts the world has ever witnessed; and Virginia, with all her social systems, will be doomed, and swept away.--New York Herald, April 19. We must also admonish the people of Maryland that we of the North have the common right of way through their State to our National Capital. But let her join the revolutionists, and her substance will be devoured by our Northern legions as by an Arabian cloud of locusts, and her slave population will disappear in a single campaign. A Northern invasion of Virginia and of Kentucky, if necessary, carrying along with it the Canadian line of African freedom, as it must do from the very nature of civil war, will produce a powerful Union reaction. The slave population of the border States will be moved in two directions. One branch of it, without the masters, will be moved Northward, and the other branch, with the masters, will be moved Southward, so that, by the time the Northern army will have penetrated to the centre of the border slave States, they will be relieved of the substance and abstract rights of slave property for all time to come. Finally, the revolted States having appealed to the sword of revolution to redress their wrongs, may soon have to choose between submission to the Union or the bloody extinction of slavery, from the absence of any law, any wish, any power for its protection.-- Ibid, April 20. By land and water, if she places herself in the attitude of rebellion, Maryland may be overrun and subdued in a single week, including the extinction of slavery within her own borders; for war makes its own laws.