Explain the quote "The Weapons with which the bourgeoisie felled feudalism to the ground are now turned against the Bourgeoisie itself"?
This quote is taken from Marx's The Communist Manifesto, and follows a discussion of how "too much civilization," too much commerce, and too much industry have come to endanger the conditions of the bourgeoisie because, as the means of production become too abundant, the bourgeoisie are no longer able to control them. Rather than continuing to become rich, the bourgeoisie become overwhelmed. Marx says that the upper class attempt to cope with this issue by destroying productive forces, at the same time as they conquer new markets and attempt once more to exploit markets that have passed. This, Marx says, only makes matters worse: the "weapons" used by the bourgeoisie to destroy feudal systems are industry and the means of production.
Now, Marx says, these weapons will be used against the bourgeoisie by the class their industry has generated: the working class, particularly the urban proletariat who have become empowered by this system. The proletariat are, according to Marx, poised on the brink of a coup because the upper class and owners of industry have set themselves up in a position to be attacked by the capitalist system they themselves have devised.
This particular concept that Marx and Engels explore helps to illuminate what they see as the imminent critique within capitalism. The argument here is that the "weapons" used by the bourgeoisie was the desire for material wealth and the coveting of profit. The belief argued was that through this profit hoarding desire and the institutional apparatus of power that supports it, the progression of material stages of history (dialectical materialism) eliminated feudalism and ushered in the stage of capitalism. At the same time, Marx and Engels argue that this is not the final stage of growth and development. Rather, that capitalism will inevitably give way to an order where the Proletariat will assume control and deconstruct the capitalist power structures. In the historical and economic inevitability which allowed the usurpation of feudal control to a capitalist order, the same fate will befall capitalism and the emergent bourgeoisie.