John Cotton Dana's remarks on a quotation suitable for inscription on a new building at Newark State College, Union, New Jersey (1912) as quoted in "The New York Times Book Review" (p. 55.), March 5, 1967.
Letter, 11 Nov. 1937, in Step by Step (1939) p. 186. Cf. the proverb "He who rides a tiger is afraid to dismount" (see Concise Oxford Dictionary of Proverbs under rides)
Ralph Waldo Emerson, Robert Ernest Spiller, Alfred Riggs Ferguson, Joseph Slater, Jean Ferguson Carr (1971). “The Collected Works of Ralph Waldo Emerson: Nature, addresses, and lectures”, p.69, Harvard University Press