Book: The Communist Manifesto

How does the bourgeoisie get over these crises? On the one hand, by enforced destruction of a mass of productive forces; on the other hand, by the conquest of new markets and more thorough exploitation of the old ones. What therefore? The fact that she's preparing more extensive and more destructive crises, and by diminishing the means of combating them.

... in those periods when the class struggle nears, the process of decomposition within the ruling class, inside of the old society takes such a violent, such a dramatic character that a small section of the ruling class renounces it and joins the revolutionary class, the class that holds the future. That's why, as before, part of the nobility passed to the bourgeoisie, so now a portion of the bourgeoisie goes over to the proletariat, it is part of the bourgeois ideologists, who have risen to the theoretical understanding of the historical movement.

In bourgeois society the past dominates the present, in Communist society the present dominates the past.

All the preceding classes that got yourself the upper hand sought to fortify their already acquired status in life, subordinating all of society to their conditions of appropriation. The proletarians cannot become the social productive forces except by abolishing their own previous mode of appropriation, and thereby also every other previous still the mode of appropriation. The proletarians have nothing of their own that would have them protect, they must destroy all that is still guarded and secured private property.

A part of the bourgeoisie is desirous of redressing social grievances in order to secure the continued existence of bourgeois society.
These include economists, philanthropists, Champions of humanity, guardians of the welfare of the working classes, organizers of charity, members of societies for protection of animals, the founding of temperance societies, melkotravchatomu reformers of various types.

In place of the old bourgeois society, with its classes and class antagonisms, we shall have an Association in which the free development of each is the condition for the free development of all.