The following is an extract from Theodore Roosevelt's biography of
Thomas H. Benton in Houghton, Mifflin, & Co.'s American Statesmen
Series, published in 1887:

"Owing to a variety of causes, the Abolitionists have received an
immense amount of hysterical praise which they do not deserve, and
have been credited with deeds done by other men whom, in reality,
they hampered and opposed rather than aided. After 1840, the
professed Abolitionists formed a small and comparatively
unimportant portion of the forces that were working towards the
restriction and ultimate destruction of slavery; and much of what
they did was positively harmful to the cause for which they were
fighting. Those of their number who considered the Constitution as
a league with death and hell, and who, therefore, advocated a
dissolution of the Union, acted as rationally as would
anti-polygamists nowadays if, to show their disapproval of
Mormonism, they should advocate that Utah should be allowed to
form a separate nation. The only hope of ultimately suppressing
slavery lay in the preservation of the Union, and every
Abolitionist who argued or signed a petition for the dissolution
was doing as much to perpetuate the evil he complained of, as if
he had been a slaveholder. The Liberty party, in running Birney,
simply committed a political crime, evil in almost all its
consequences. They in no sense paved the way for the Republican
party, or helped forward the Anti-Slavery cause, or hurt the
existing organizations. Their effect on the Democracy was _nil_;
and all they were able to accomplish with the Whigs was to make
them put forward for the ensuing election a slaveholder from