In many ways biographies of Marx (and Engels) are just what are needed to portray the saga of early socialism but we should keep in mind that Marx himself refused to get specific about the nature of that socialism or a socialist society. We should be mindful of this and not try to push Marx’s theories beyond their limits. Marx explicitly left the tasks of socialism/communism to the future and no doubt that was appropriate in his time, but we must then remember that we have to go beyond Marx, as he enjoined, and speak to our own time with specific constructs of social models that can realize a future postcapitalism. We should note that the failure to do this during the Russian revolution ended up with Stalin filling in the blanks in the vacuum left by ‘socialists’/’communists’. Leftists are constantly scrounging through Marx’s works for indications about what socialism is or should be. But there is nothing there to do that. We find a lot of cogent critique of classical economics, but that is long gone now in the era of neo-classical economics. we have another task, just what Marx predicted would happen. Thus the inspiration of biographical accounts is pretty much all that we can inherit from Marx. There is a larger use of Marx beyond his specifics: if we look at the rise of modern economics we find a developing set of unchallenged assumptions and it is significant that Marx and Engels suddenly appear to create a dialectical challenge to the emergence of modern economic systems suddenly overtaken by a peculiar kind of capitalism well analyzed by Adam Smith, but then malevolently mutating into the strange monstrosity that confronted Marx. And Marx’ response was simply to challenge the legitimacy of that outcome which had in any case been complicated from the start by its dark side, viz. the question of slavery. If Marx had done nothing else that would have been enough. But Marx’s tendencies to theory complicated his legacy: consider the stages of production theory with its progression of epochs: the result is a crypto-teleological theory of history which doesn’t specify what the ‘epoch’ of postcapitalism will be, simply labelled ‘communism’ We cannot make a mechanical prediction about a system that doesn’t define the key final epoch, ‘communism’ and the result we see in the way the bolshevik moment derailed in the fog of that non-definition.
We do Marx better justice with a creative attempt to recast, better, set aside his theories, and consider his key achievement: shattering the pseudo-scientific complacency of the classical economists, and challenging the rapidly self-sanctifying ‘legitimacy’ of the new economic system overtaking modernity and usurping its definition.
Let us recall that with Thomas Munzer the idea of modern communism is the first born of the era of emergent modernity: capitalism is a spurious and ad hoc conglomeration of elements and attempts to become its defining standard to the point of a spurious recasting of ethical principles with respect to acquisitiveness…

https://www.amazon.com/Karl-Marx-Birth-Modern-Society/dp/1583677356/ref=sr_1_1?keywords=Karl+Marx+and+the+Birth+of+Modern+Society&qid=1560505993&s=books&sr=1-1

arl Marx and the Birth of Modern Society: