Carlyle wrote On Heroes, Hero-Worship, & the Heroic in History, which Thoreau considered his crowning achievement.
Thoreau appreciated the attitude of those who would not settle to think pre-conceived thoughts, but who instead wished to break out of the box of religious tradition and think independently for oneself.
Thoreau thought Carlyle to be of the "Reformer class" and that he had greatly contributed to humanity through his writings.
"The end of man is an action and not a thought, though it be the noblest," Carlyle wrote, and Thoreau sums up Carlyle's philosophy in this way: One thing is certain – that we had best be doing something in good earnest henceforth forever; that's an indispensable philosophy.
Carlyle reported to Emerson that it was "carefully read, as beseemed, with due entertainment and recognition."