As in this Enterprise there is a place for every argument, so also is there a place for every man. Even as on the broad shield of Achilles, sculptured by divine art, was wrought every form of human activity, so in this cause, which is the very shield of Freedom, whatever man can do by deed or speech will find its place. One may act in one way, and another in another way; but all must act. Providence is felt through individuals; the dropping of water wears away the rock; and no man can be too humble or poor for this work, while to all the happy in genius, fortune, or fame it makes a special appeal. Here is room for the strength of Luther and the sweetness of Melancthon, for the wisdom of age and the ardor of youth, for the judgment of the statesman and the eloquence of the orator, for the grace of the scholar and the aspiration of the poet, for the learning of the professor and the skill of the lawyer, for the exhortation of the preacher and the persuasion of the press, for the various energy of man and the abounding sympathy of woman. And still one thing more is needed, without which Liberty-loving men, and their arguments, will fail in power,--even as without charity all graces of knowledge, speech, and faith are said to profit nothing. I mean that _Unity of Spirit_--in itself a fountain of strength--which, filling the people of the North, shall make them tread under foot past antipathies, decayed dissensions, and those irritating names which now exist only as tattered ensigns of ancient strife. It is right to be taught by the enemy; and with their example before us, and their power brandished in our very faces, we cannot hesitate. With them Slavery is the mainspring of political life, and the absorbing centre of political activity; with them all differences are swallowed up by this _one idea_, as all other rods were swallowed up by the rod of Aaron; with them all unite to keep the National Government under the control of slave-masters: and surely we should not do less for Freedom than they do for Slavery. _We, too, must be united._ Among us at last mutual criticism, crimination, and feud must give place to mutual sympathy, trust, and alliance. Face to face against the Slave Oligarchy must be rallied the UNITED MASSES of the North, in compact political association,--planted on the everlasting base of justice,--knit together by instincts of a common danger and holy sympathies of humanity,--enkindled by love of Freedom, not only for themselves, but for others,--determined to enfranchise the National Government from degrading thraldom,--and constituting the BACKBONE PARTY, powerful in numbers, wealth, and intelligence, but more powerful still in an inspiring cause. Let this be done, and victory will be ours. NEW OUTRAGE FOR THE SAKE OF SLAVERY. LETTER TO PASSMORE WILLIAMSON, IN MOYAMENSING PRISON, AUGUST 11, 1855.