<<Does anyone have a reference, or better still some context, for German Socialist August Bebel's comment that "Anti-Semitism is the socialism of fools" (1893?).>>
I can't put my finger on the source of Bebel's famous quotation, but to put it in context, he seems to have been describing a stage of (false) consiousness which could serve as a point of entry for marxists to offer their analysis, winning workers away from "Chistian socialist" parties, thus helping the workers to advance from foolishness to wisdom, I would guess.
Here are passages from a couple of books which deal with this:
"The SPD leaders also rejected the defense of specifically Jewish religious issues and were far from philo-Semitic. In 1908 the Central Association of German Citizens of Jewish Faith (CV) was of the opinion that the SPD would oppose attempts to curtail Jewish rights, 'But when it is a question of the threatened reiligious interests of the Jews, the Social Democrats in view of their principles cannot speak out for them, and the Social Democrats also will not ignore the fact that they may hope for a rich harvest wherever antisemitism has ploughed the soil.'" (Sarah Gordeon,HITLER, GERMANS AND THE 'JEWISH QUESTION', 1984, Princeton U.P., p.38)
"An examination of Bernstein's writings of the early 1890s reveals, for example, that he thought of the anti-Semitic movement as a 'connecting link' between the reactionary parties and socialists, and that he described the anti-Semitic movement as a 'first stage' on the road to socialism--very much in the same way as did Engles and Bebel during the same period." (Jack Jacobs, ON SOCIALISTS AND 'THE JEWISH QUESTION' AFTER MARX, 1992, New York UP, p.59)
K. Mickey