I suppose you think that persons who are as old as your father and myself are always thinking about very grave things, but I know that we are meditating the same old themes that we did when we were ten years old, only we go more gravely about it.
Source: Letter, 31 Jul 1849, to Ellen Emerson (then 10 years old), eldest child of Ralph Waldo Emerson.
-- Henry David Thoreau, (Jul 12 1817-1862), US essayist, poet, naturalist; He is best known for his description of life at Walden Pond, Walden, 1854 and his essay Civil Disobedience, 1849.