Selig Perlman, A History of Trade Unionism in the United States
“ From the standpoint of socialism no more unfortunate step could have been taken. It immediately stamped the socialists as wilful destroyers of the unity of labor. To the trade unionists, yet fresh from the ordeal of the struggle against the Knights of Labor, the action of the socialists was an unforgivable crime. All the bitterness which has characterized the fight between socialist and anti-socialist in the Federation verily goes back to this gross miscalculation by DeLeon of the psychology of the trade union movement. ”
