Born in Prague, the son of Jewish parents, a painter and an actress and author of novels admired by Engels. During his childhood, the family moved to Vienna. In 1874 Kautsky joined the Austrian social democracy, and in 1880 a group of socialists in Zurich. Under the influence of Eduard Bernstein, was a Marxist in 1881 and visited Marx and Engels in London. In 1890, after the derrogación of anti-socialist laws, settled in Berlin with his second wife, Luise Ronsperger (1864-1944). That was one of the founders of the German Social Democratic (SPD) Party, writing several of their programs and platforms. Later, when Bernstein, in his book Evolutionary Socialism, attacked the Marxist position on the objective necessity of revolution, Kautsky criticized and defended the positions of Marx and Engels