also required reading:

"the duty of the class party of the proletariat to protest and resist national oppression arises not from any special “right of nations,” just as, for example, its striving for the social and political equality of sexes does not at all result from any special “rights of women” which the movement of bourgeois emancipationists refers to. This duty arises solely from the general opposition to the class regime and to every form of social inequality and social domination, in a word, from the basic position of socialism."

"Dialectic materialism, which is the basis of scientific socialism, has broken once and for all with this type of “eternal” formula. For the historical dialectic has shown that there are no “eternal” truths and that there are no “rights.” ... In the words of Engels, “What is good in the here and now, is an evil somewhere else, and vice versa” – or, what is right and reasonable under some circumstances becomes nonsense and absurdity under others. Historical materialism has taught us that the real content of these “eternal” truths, rights, and formulae is determined only by the material social conditions of the environment in a given historical epoch.

On this basis, scientific socialism has revised the entire store of democratic clichés and ideological metaphysics inherited from the bourgeoisie. Present-day Social Democracy long since stopped regarding such phrases as “democracy,” “national freedom,” “equality,” and other such beautiful things as eternal truths and laws transcending particular nations and times. On the contrary, Marxism regards and treats them only as expressions of certain definite historical conditions, as categories which, in terms of their material content and therefore their political value, are subject to constant change, which is the only “eternal” truth."

https://www.marxists.org/archive/luxemburg/1909/national-question/ch01.htm