"No detailed outlines of these, or any of his other literary undertakings are to be found; but it must not be inferred that such memoranda contain mere projects, towards whose execution no steps were ever taken. That Niebuhr proposed any such work to himself, was a certain sign that he had read and thought deeply on the subject, but he was able to trust so implicitly to his extraordinary memory, that he never committed any portion of his essays to paper, till the whole was complete in his own mind. His memory was so wonderfully retentive, that he scarcely ever forgot any thing which he had once heard or read, and the facts he knew remained present to him at all times, even in their minutest details. "His wife and his sister once playfully took up Gibbon, and asked him questions from the table of contents about the most trivial things, by way of testing his memory. They carried on the examination till they were tired, and gave up all hope of even detecting him in a momentary uncertainty, though he was at the same time engaged in writing on some other subject. He was once conversing with a party of Austrian officers about Napoleon's Italian campaigns. Some dispute arose respecting the position of different corps in the battle of Marengo. Niebuhr described exactly how they were placed, and the progress of the action. The officers contradicted him; but on maps being brought he was found to be in the right, and to know more of the details of the conflict than the very officers who had been present. One day, when he was talking with Professor Welcker of Bonn, the conversation happened to turn on the weather, and Niebuhr quoted the results of barometrical observations in the different years, as far back as 1770, with perfect accuracy. This power was not a merely mechanical faculty; it was intimately connected with the power of instantaneously seizing on all the relations of any fact placed before him, and with his wonderful imagination; his imagination, however, was that of an historian, not of a poet--it was not creative, but enabled him to form from the most various, and apparently inadequate sources, distinct and truthful pictures of scenes, actions, and characters. Hence his keen delight in travels: hence, too, his habit of pronouncing judgment on the men of other countries and of past times, with all the warmth of a fellow-countryman and a contemporary. "With his warm affections, and clear-sighted moral sense, it was impossible for him to form such opinions on past or present history, coolly standing aloof, as it were, and regarding the subject with calm superiority; he could not but condemn and despise all that was pernicious and base; he could not but love and reverence, with his whole heart, whatever was noble and beautiful. Such opinions and feelings he expressed with the utmost frankness, sometimes even with vehemence, when prudence would have counselled more guarded language."