The same peculiarity can be discerned in his letters. The fun and humor which had hitherto run through his correspondence seems now to fade away as if blighted. On September 10, 1850, he writes to Mr. Harvey that since March 7 there has not been an hour in which he has not felt a “crushing sense of anxiety and responsibility.” He couples this with the declaration that his own part is acted and he is satisfied; but if his anxiety was solely of a public nature, why did it date from March 7, when, prior to that time, there was much greater cause for alarm than afterwards. In everything he said or wrote he continually recurs to the slavery question and always in a defensive tone, usually with a sneer or a fling at the abolitionists and anti-slavery party. The spirit of unrest had seized him. He was disturbed and ill at ease. He never admitted it, even to himself, but his mind was not at peace, and he could not conceal the fact. Posterity can see the evidences of it plainly enough, and a man of his intellect and fame knew that with posterity the final reckoning must be made. No man can say that Mr. Webster anticipated the unfavorable judgment which his countrymen have passed upon his conduct, but that in his heart he feared such a judgment cannot be doubted.
It is impossible to determine with perfect accuracy any man’s motives in what he says or does. They are so complex, they are so often undefined, even in the mind of the man himself, that no one can pretend to make an absolutely correct analysis. There have been many theories as to the motives which led Mr. Webster to make the 7th of March speech. In the heat of contemporary strife his enemies set it down as a mere bid to secure Southern support for the presidency, but this is a harsh and narrow view. The longing for the presidency weakened Mr. Webster as a public man from the time when it first took possession of him after the reply to Hayne. It undoubtedly had a weakening effect upon him in the winter of 1850, and had some influence upon the speech of the 7th of March. But it is unjust to say that it did more. It certainly was far removed from being a controlling motive. His friends, on the other hand, declare that he was governed solely by the highest and most disinterested patriotism, by the truest wisdom. This explanation, like that of his foes, fails by going too far and being too simple. His motives were mixed. His chief desire was to preserve and maintain the Union. He wished to stand forth as the great saviour and pacificator. On the one side was the South, compact, aggressive, bound together by slavery, the greatest political force in the country. On the other was a weak Free-Soil party, and a widely diffused and earnest moral sentiment without organization or tangible political power. Mr. Webster concluded that the way to save the Union and the Constitution, and to achieve the success which he desired, was to go with the heaviest battalions. He therefore