… is from page 304 of the 1981 Liberty Fund edition of the 1936 J. Kahane translation of Ludwig von Mises’s great 1922 volume, Socialism :
In principle class ideology is no different from national ideology. In fact there is no contrast between the interests of particular nations and races. It is national ideology which first creates the belief in special interests and turns nations into special groups which fight each other. Nationalist ideology divides society vertically; the socialist ideology divides society horizontally. In this sense the two are mutually exclusive.