Charles: I'm trying to understand your point as a response to Angela. Her main point (excuse my presumptiveness, Angela) is that, while class struggle has always existed, capitalism created a new form of class relations. That is, a new class was created, capitalists, that led to the unequal exchange between capital and labor in the labor market, which forms the basis for the new exploitation of labor by capital, as well as the contradictions inherent in capitalism as a system. Labor sells its labor power to live (reproduce itself); capitalists accumulate the surplus value they extract from labor.
I don't think you disagree with that.
So, is your quarrel here only with the notion that the Manifesto is more than a mere story, but rather offers organizational value? If so, OK.
But I don't agree with the further point that the Manifesto is "more serious" (more valuable?) than some of the "theorizing" in the 3 volumes (if that's what you mean by "other more theoretical discussions"). When Mao asked "where do ideas come from" and concluded that they come out of praxis, he was performing the essence of Marxism as he understood it. But the dialectic also requires thought to inform practice. And that has always turned out to be the hard part, hasn't it, that part about understanding the central contradictions under today's conditions so that actions can be focused and make sense?
Like no one before, Marx pieced together the practice of his day and explained its essence--the laws of motion of capitalism. Not discounting his efforts to organize workers based on the conditions of his time, but *that* was really important to the future of the class struggle.