This explains the chief difference in the attitude of the two leaders.

Sumner, like Adams, began as an opponent of pro-slavery aggression, but he went farther: he attacked the institution itself as a great moral evil.
As a constitutional lawyer Sumner is not the equal of his predecessor, Daniel Webster.

He is less original, less convincing in the enunciation of broad general principles.

He appears rather as a special pleader marshaling all available forces against the one institution which assailed the Union.

In this particular work, he surpassed all others, for, with his unbounded industry, he permitted no precedent, no legal advantage, no incident of history, no fact in current politics fitted to strengthen his cause, to escape his untiring search.