GENTLEMEN,--I resign most reluctantly the opportunity with which I am favored by your invitation, and shall try to content myself with reading the report of your powerful and well-organized meeting at Chicago, without taking part in it. The proposition to unite the greatest navigable river of the world with the greatest inland sea is characteristic of the West. Each is worthy of the other. The idea of joining these together strikes the imagination as original. But the highest beauty is in utility, which will not be wanting here. With this union, the Gulf of Mexico will be joined to the Gulf of St. Lawrence, and the whole continent, from Northern cold to Southern heat, traversed by one generous flood, bearing upon its bosom untold commerce. It is for the West to consider well the conditions of this enterprise, and the advantages it will secure. Let its practicability be demonstrated, and the country will command it to be done, as it has already commanded the opening of the Mississippi. Triumphant over the wickedness of an accursed Rebellion, we shall achieve another triumph, to take its place among the victories of Peace. To this magnificent work Science will contribute her myriad resources. But there is something needed even to quicken and inspire science: it is the unconquerable will, which does not yield to difficulties, but presses forward to overcome them. No word is used with more levity than the word “impossible.” A scientific professor, in a public address, declared the navigation of the Atlantic by steam “impossible.” Within a few weeks it was done. The British Prime-Minister declared the construction of a canal between the Mediterranean and the Red Sea “impossible.” The Pacha of Egypt, with French engineers, is now doing it. Mirabeau was right, when he protested against the use of this word as simple stupidity. But I doubt if the word will be found in any Western dictionary. Believe me, Gentlemen, with much respect, Very faithfully yours, CHARLES SUMNER. To Hon. JAMES ROBB, I. N. ARNOLD, and others of the Committee. THE ISSUES OF THE WAR. DEDICATION OF A NEW EDITION OF THE SPEECH ON THE BARBARISM OF SLAVERY,[152] JULY 4, 1863. TO THE YOUNG MEN OF THE UNITED STATES I DEDICATE THIS NEW EDITION OF A SPEECH ON THE BARBARISM OF SLAVERY, IN TOKEN OF HEARTFELT GRATITUDE TO THEM FOR BRAVE AND PATRIOTIC SERVICE RENDERED IN THE PRESENT WAR FOR CIVILIZATION.