"The Russian Marxists have long had their theory of the nation.
According to this theory, a nation is a historically constituted,
stable community of people, formed on the basis of the common 
possession of four principal characteristics, namely: a common
language, a common territory, a common economic life, and a common
psychological make-up manifested in common specific features of
national culture. This theory, as we know, has received general
recognition in our Party.

"It is evident from your letters that you consider this theory 
inadequate. You therefore propose that the four characteristics
of a nation be supplemented by a fifth, namely, that a nation
possesses its own, separate national state. You consider that
there is not and cannot be a nation unless this fifth 
characteristic is present.

I think that the scheme you propose, with its new, fifth
characteristic of the concept 'nation,' is profoundly
mistaken and cannot be justified either theoretically or in 
practice, politically."

J. Stalin, March 18, 1929, "The National Question 
and Leninism: Reply to Comrades Meshkov, 
Kovalchuk, and Others" <I>Works</I> Vol. 11
(Moscow: Foreign Languages Publishing House, 1954)

[MC5 comments:
From the above, we see that Stalin wanted to be careful to
make sure that his comrades understood why communists theorize
about nationhood. Classes and nations both are useful to come
up with strategies for progressive change. We don't worship
past or present classes and the same for existing bourgeois nation-states.]