As socialism is more and more constructed, the class struggle does not disappear, and even does not get any weaker. The class struggle under socialism does not end, but acquires a new shape, it goes on as that of a proletarian (Communist) creative tendency against the petty-bourgeois tendency of private ownership. An indispensable feature (characteristics) of socialism is the power, that exercises the proletarian dictatorship and provides the victory of the positive Communist tendency.
The new socialist society, that had just recently completed the stage of open struggle with the exploiters, would necessarily be confronted with another, hidden, but no less dangerous forms of class struggle.
The essence of this point was very well described in the speech of Joseph Stalin “About industrialization and the bread problem” (July,9 1928):
“We often say that we are promoting socialist forms of economy in the sphere of trade. But what does that imply? It implies that we are squeezing out of trade thousands upon thousands of small and medium traders. Is it to be expected that these traders who have been squeezed out of the sphere of trade will keep silent and not attempt to organise resistance? Obviously not.
We often say that we are promoting socialist forms of economy in the sphere of industry. But what does that imply? It implies that, by our advance towards socialism, we are squeezing out and ruining, perhaps without ourselves noticing it, thousands upon thousands of small and medium capitalist manufacturers. Is it to be expected that these ruined people will keep silent and not attempt to organise resistance? Of course not.
We often say that it is necessary to restrict the exploiting proclivities of the kulaks in the countryside, that they must be heavily taxed and the right to rent land limited, that kulaks must not be allowed the right to vote in the election of Soviets, and so on and so forth. But what does that imply? It implies that we are gradually pressing upon and squeezing out the capitalist elements in the countryside, sometimes driving them to ruin. Is it to be presumed that the kulaks will be grateful to us for this and will not endeavour to organise part of the poor peasants or middle peasants against the Soviet Government's policy? Of course not.
Is it not obvious that our whole forward movement, our every success of any importance in the sphere of socialist construction, is an expression and result of the class struggle in our country?
But it follows from all this that the more we advance, the greater will be the resistance of the capitalist elements and the sharper the class struggle, while the Soviet Government, whose strength will steadily increase, will pursue a policy of isolating these elements, a policy of demoralizing the enemies of the working class, a policy, lastly, of crushing the resistance of the exploiters, thereby creating a basis for the further advance of the working class and the main mass of the peasantry.
It must not be imagined that the socialist forms will develop, squeezing out the enemies of the working class, while our enemies retreat in silence and make way for our advance, that then we shall again advance and they will again retreat until "unexpectedly" all the social groups without exception, both kulaks and poor peasants, both workers and capitalists, find themselves "suddenly" and "imperceptibly," without struggle or commotion, in the lap of a socialist society. Such fairy-tales do not and cannot happen in general, and in the conditions of the dictatorship of the proletariat in particular.
It never has been and never will be the case that a dying class surrenders its positions voluntarily without attempting to organise resistance. It never has been and never will be the case that the working class could advance towards socialism in a class society without struggle or commotion. On the contrary, the advance towards socialism cannot but cause the exploiting elements to resist the advance, and the resistance of the exploiters cannot but lead to the inevitable sharpening of the class struggle“. 
We need to say, that in the period of Gorbachev’s perestroika and some later, in the period of the capitalist restoration in the USSR, there were frequent attacks of the class struggle aggravation at the extent of approaching to socialism on the Stalin’s formula, coming from the leaders of counter-revolution. Some attackers were even trying to mock and to speak ironically as if Joseph Stalin alledgedly was short-sighted and ignored the contradiction: Communism is closer and closer and the class struggle goes on to sharpen and there is no end to it.
However, history has proved, that it was Stalin, who was right, and not his critics from the right and the “leftest” camps. The contradiction of the class struggle aggravation as socialism is being built formula has a dialectical character. The moribund classes will never know rest until they try absolutely all possible ways how to prevent the construction of socialism and to terminate this historical process. Petty-bourgeois tendencies usually gather their pace when there appears a a certain gap (problem) in the practice of socialism. To monitor this process is the main function of the proletarian dictatorship.
We know, that after the death of Joseph Stalin the bourgeois tendencies in the USSR took a new shape. The shadow (dark) economy, corruption, profiteering, localistic tendencies and nationalism, that were not finally smashed, gradually started their offensive. Anti-Soviet spirits penetrated into the Communist Party, the state organs and special services. The situation was aggravated by the circumstance, that since approximately the middle of 1950s the Soviet people stopped to feel itself a militant detachment of revolution, they got accustomed to victories and started to think, that capitalism is defeated forever, that all harmful phenomena, that are still retained in the USSR, are temporary; that socialism in our country is already constructed and is irreversible.
Instead of a class mobilization for fighting the enemy in its new form, the Soviet people, including old party cadre, displayed their mass placidity and quietly commissioned the struggle with the enemy to the state security services.
it was, certainly, absolutely insufficient at all. Besides, localist interests, corruption and bourgeois tendencies were imperceptibly developing in security services too.
All bourgeois tendencies, that were not subdued before, had not missed their opportunity at the moment of weakening of the proletarian dictatorship and played the role of an advanced detachment of the counter-revolution in the end of 1980s.
One should not forget, that even a ripe and mature socialism contains simultaneously two opposite tendencies: a socialist tendency and a capitalist, petty-bourgeois one. Until a complete Communism is constructed in the whole World, the capitalist tendency will impede any movement forward in every way and even try to return history backwards. In conditions of the socialist society it is necessary to constantly struggle with the negative capitalist tendency – not only never forget about it, but also spare no efforts and recourses to completely eradicate it. The Communist party and workers in the USSR had forgotten about this dialectics of struggle in the last decades of the USSR, that had led to catastrophic consequences.
The Marxist theory does not dictate any detailed remedies and ideal models of the socialist society. Marx and Engels wrote, that Communism is not a state, that should be established, and not an ideal, to which a reality should be adjusted. They called communism a real movement, that negates the current state of things, that is unjust and hampering the development of the society.
Socialism is such as it came out-of capitalism depending on current conditions. It can be vigorous, wicked, not replete and even bloody. As we concluded, the class struggle is not over under socialism, but it takes a new form, it hoes on as the struggle of a proletarian, Communist and creative tendency against the petty-bourgeois tendency of private ownership. An obligatory characteristics of socialism is the power, that exercises the proletarian dictatorship and provides the victory of a positive Communist tendency.
The socialism is characterized:
In the political field socialism, according to Lenin’s definition, is an elimination of classes. I.e. the movement to overcome class differences, differences between manual and intellectual labor and so on. V. I. Lenin clarifies, that “The abolition of classes requires a long, difficult and stubborn class struggle, which, after the overthrow of capitalist rule, after the destruction of the bourgeois state, after the establishment of the dictatorship of the proletariat, does not disappear (as the vulgar representatives of the old social-ism and
the old Social-Democracy imagine), but merely changes its forms and in many respects becomes fiercer“. 
In the field of economic relations socialism is the overcoming of the commodity production elements and momentum in immediately social production.
In the moral respect socialism provides ever growing opportunities development of everyone and anyone.