They have markedly influenced the opinion of men about the past. It is commonly said that Hume's _History of England_, defective as it is, has yet "by its method revolutionized the writing of history," and that is true. Nearer our own time, Carlyle's _Life of Cromwell_ reversed the judgment of history on Cromwell, gave all readers of history a new conception of him and his times and of the movement of which he was the life. After the Restoration none were so poor as to do Cromwell reverence until Carlyle's _book_ gave him anew to the world. There are instances squarely in our own time by which their mighty influence may be tested. They are of books of almost ephemeral value save for the student of history. As literature they will be quickly forgotten; but as _forces_ they must be reckoned with. There is _Uncle Tom's Cabin_. It would be absurd to say that it brought the American Civil War, or freed the negroes, or saved the Union. It did none of those great things. Yet it is not at all absurd to name it among the potent powers in all three. It is not to our purpose whether it is true or not as a statement of the whole fact. Doubtless it was not true of the general and common circumstances of Southern slavery; but everything in it was possible, and even frequent enough so that it could not be questioned. It pretended no more. But its influence was simply tremendous. In book form it became available in 1852, and within three years, 1855, it was common property of English-speaking people. No other book ever produced so extraordinary an effect so quickly in the public mind.[41] It held up slavery to judgment. It crystallized the thoughts of common people. The work of those strenuous years in the '60's could not have been done without the result of that book. It made history. Come nearer our own day. We could not be long in London without feeling the concern of the better people for conditions in the East End. A new social impulse has seized them. To be sure, it lacks much yet of success; but more has been done than most people realize. The new movement, the awakening of that social sense, traces back to the book of Gen. William Booth, _In Darkest England_ (1890). It has helped to change the life of a large part of London. On this side, the new concern for city conditions dates from the book of a newspaper reporter, Jacob A. Riis, _How the Other Half Lives_. It thrust the Other Half into such prominence that it has never been possible to forget it. Marked advance in all American cities, in legislation and life, goes straight back to it. Name one other book still in the field of social service, even so unpleasant, so terrible, so obnoxious a book as Upton Sinclair's _The Jungle_. It started and sustained movements which have unsettled business and political life ever since it appeared. It made some conditions vivid, unescapable.