“Almost all the noblest things that have been achieved in the world, have been achieved by poor men; poor scholars, poor professional men, poor artisans and artists, poor philosophers, poets, and men of genius.”

that's my slogan.
Huey Long (T. Harry Williams, Huey Long, p. 706)

Source: Water Sleeps (1999), Chapter 87 (p. 314)

Source: Bleak House (1852-1853), Ch. 28

Attributed to Charles Barkley in Walter W. Moore's Wise Sayings (2012), p. 89

1960s, The Quest for Peace and Justice (1964)

Compare Poor Richard's Almanack (1735) : The poor man must walk to get meat for his stomach, the rich man to get a stomach to his meat.
Introductio ad prudentiam: Part II (1727), Gnomologia (1732)

Source: The Traveller (1764), Line 386.

I Think I'll Sit This One Out (1939)
Context: If I believed that force would ever build a better world, I would be a Marxist revolutionary. But I have no more faith in poor men's animalism than in rich men's. And I want no proletarian revolution until the proletariat has demonstrated devotion to reason which the rich, with larger opportunities to cultivate that virtue, have so universally failed to achieve. I favor the underdog against the upperdog, but I favor something better than a dog above both of them.

“Arizona and New Mexico: On Top”, p. 126.
A Sand County Almanac, 1949, "Arizona and New Mexico: On Top," & "Arizona and New Mexico: Thinking Like a Mountain"