A liberal is a man too broadminded to take his own side in a quarrel.
Source, in full
Attributed to Frost in Harvey Shapiro "Story of the Poem", The New York Times (January 15, 1961), sec. SM, p. 6; and in Guy Davenport, The Geography of the Imagination (San Francisco: North Point Press, 1981), p. 208. An earlier unattributed version of this quip appeared in William Ernest Hocking, What Man Can Make of Man (1942): "He lends himself to the gibe that he is 'so very liberal, that he cannot bring himself to take his own side in a quarrel.'"