Quoted in "Premier Chou Enlai's Report on the Work of the Government to the First Session of the Third National People's Congress of the People's Republic of China" (December 21-22, 1964).

Natural science is one of man's weapons in his fight for freedom. For the purpose of attaining freedom in society, man must use social science to understand and change society and carry out social revolution. For the purpose of attaining freedom in the world of nature, man must use natural science to understand, conquer and change nature and thus attain freedom from nature.

Speech at the inaugural meeting of the Natural Science Research Society of the Border Region (February 5, 1940).

The Marxist philosophy of dialectical materialism has two outstanding characteristics. One is its class nature: it openly avows that dialectical materialism is in the service of the proletariat. The other is its practicality: it emphasizes the dependence of theory on practice, emphasizes that theory is based on practice and in turn serves practice.

"On Practice" (July 1937), Selected Works,  Vol. I, p. 297.

Marxist philosophy holds that the most important problem does not lie in understanding the laws of the objective world and thus being able to explain it, but in applying the knowledge of these laws actively to change the world.

Ibid.,  p. 304.

Where do correct ideas come from? Do they drop from the skies? No. Are they innate in the mind? No. They come from social practice, and from it alone; they come from three kinds of social practice, the struggle for production, the class struggle and scientific experiment.

Where Do Correct Ideas Come from?  (May 1963), 1st pocket ed., p. 1.

It is man's social being that determines his thinking. Once the correct ideas characteristic of the advanced class are grasped by the masses, these ideas turn into a material force which changes society and changes the world.

Ibid. 

In their social practice, men engage in various kinds of struggle and gain rich experience, both from their successes and from their failures. Countless phenomena of the objective external world are reflected in a man's brain through his five sense organs - the organs of sight, hearing, smell, taste and touch. At first, knowledge is perceptual. The leap to conceptual knowledge, i e., to ideas, occurs when sufficient perceptual knowledge is accumulated. This is one process in cognition. It is the first stage in the whole process of cognition, the stage leading from objective matter to subjective consciousness, from existence to ideas. Whether or not one's consciousness or ideas (including theories, policies, plans or measures) do correctly reflect the laws of the objective external world is not yet proved at this stage, in which it is not yet possible to ascertain whether they are correct or not. Then comes the second stage in the process of cognition, the stage leading from consciousness back to matter, from ideas back to existence, in which the knowledge gained in the hrst stage is applied in social practice to ascertain whether the theories, policies, plans or measures meet with the anticipated success. Generally speaking, those that succeed are correct and those that fail are incorrect, and this is especially true of man's struggle with nature. In social struggle, the forces representing the advanced class sometimes suffer defeat not because their ideas are incorrect but because, in the balance of forces engaged in struggle, they are not as powerful for the time being as the forces of reaction; they are therefore temporarily defeated, but they are bound to triumph sooner or later. Man's knowledge makes another leap through the test of practice. This leap is more important than the previous one. For it is this leap alone that can prove the correctness or incorrectness of the first leap in cognition, i.e., of the ideas, theories, policies, plans or measures formulated in the course of reflecting the objective external world. There is no other way of testing truth.

Ibid.,  pp. 1-3.*

Often, correct knowledge can be arrived at only after many repetitions of the process leading from matter to consciousness and then back to matter, that is, leading from practice to knowledge and then back to practice. Such is the Marxist theory of knowledge, the dialectical materialist theory of knowledge.

Ibid.,  P. 3.*

Whoever wants to know a thing has no way of doing so except by coming into contact with it, that is, by living (practising) in its environment. ... If you want knowledge, you must take part in the practice of changing reality. If you want to know the taste of a pear, you must change the pear by eating it yourself.... If you want to know the theory and methods of revolution, you must take part in revolution. All genuine knowledge originates in direct experience.

"On Practice" (July 1937), Selected Works,  Vol. I, pp. 299-300.

Knowledge begins with practice, and theoretical knowledge which is acquired through practice must then return to practice. The active function of knowledge manifests itself not only in the active leap from perceptual to rational knowledge, but - and this is more important - it must manifest itself in the leap from rational knowledge to revolutionary practice.

Ibid.,  p. 304.*

It is well known that when you do anything, unless you understand its actual circumstances, its nature and its relations to other things, you will not know the laws governing it, or know how to do it, or be able to do it well.

"Problems of Strategy in China's Revolutionary War" (December 1936), Selected Works,  Vol. I, p. 179.

If a man wants to succeed in his work, that is, to achieve the anticipated results, he must bring his ideas into correspondence with the laws of the objective external world; if they do not correspond, he will fail in his practice. After he fails, he draws his lessons, corrects his ideas to make them correspond to the laws of the external world, and can thus turn failure into success; this is what is meant by "failure is the mother of success" and "a fall into the pit, a gain in your wit".

"On Practice" (July 1937), Selected Works,  Vol. I, pp. 296-97.

We are Marxists, and Marxism teaches that in our approach to a problem we should start from objective facts, not from abstract definitions, and that we should derive our guiding principles, policies and measures from an analysis of these facts.

"Talks at the Yenan Forum on Literature and Art" (May 1942), Selected Works,  Vol. III, p. 74.

The most fundamental method of work which all Communists must firmly bear in mind is to determine our working policies according to actual conditions. When we study the causes of the mistakes we have made, we find that they all arose because we departed from the actual situation at a given time and place and were subjective in determining our working policies.

"Speech at a Conference of Cadres in the Shansi-Suiyuan Liberated Area" (April 1, 1948), Selected Works,  Vol. IV, pp. 229-30.*

Idealism and metaphysics are the easiest things in the world, because people can talk as much nonsense as they like without basing it on objective reality or having it tested against reality. Materialism and dialectics, on the other hand, need effort. They must be based on and tested by objective reality. Unless one makes the effort one is liable to slip into idealism and metaphysics.

Introductory note to "Material on the Hu Feng Counter-Revolutionary Clique" (May 1955).

When we look at a thing, we must examine its essence and treat its appearance merely as an usher at the threshold, and once we cross the threshold, we must grasp the essence of the thing; this is the only rcliable and scientific method of analysis.

"A Single Spark Can Start a Prairie Fire" (January 5, 1930), Selected Works,  Vol. I, p. 119.

The fundamental cause of the development of a thing is not external but internal; it lies in the contradictoriness within the thing. This internal contradiction exists in every single thing, hence its motion and development. Contradictoriness within a thing is the fundamental cause of its development, while its interrelations and interactions with other things are secondary causes.

"On Contradiction" (August 1937), Selected Works,  Vol. I, p. 313.

It [materialist dialectics] holds that external causes are the condition of change and internal causes are the basis of change, and that external causes become operative through internal causes. In a suitable temperature an egg changes into a chicken, but no temperature can change a stone into a chicken, because each has a different basis.

Ibid.,  p. 314.

Marxist philosophy holds that the law of the unity of opposites is the fundamental law of the universe. This law operates universally, whether in the natural world, in human society, or in man's thinking. Between the opposites in a contradiction there is at once unity and struggle, and it is this that impels things to move and change. Contradictions exist everywhere, but they differ in accordance with the different nature of different things. In any given phenomenon or thing, the unity of opposites is conditional, temporary and transitory, and hence relative, whereas the struggle of opposites is absolute.

On the Correct Handling of Contradictions Among the People  (February 27, 1957), 1st pocket ed., p. 18.

The analytical method is dialectical. By analysis, we mean analysing the contradictions in things. And sound analysis is impossible without intimate knowledge of life and without real understanding of the pertinent contradictions.

Speech at the Chinese Communist Party's National Conference on Propaganda Work  (March 12, 1957), l5t pocket ed., p. 20.

Concrete analysis of concrete conditions, Lenin said, is "the most essential thing in Marxism, the living soul of Marxism". Lacking an analytical approach, many of our comrades do not want to go deeply into complex matters, to analyse and study them over and over again, but like to draw simple conclusions which are either absolutely affirmative or absolutely negative.... From now on we should remedy this state of affairs.

"Our Study and the Current Situation" (April 12, 1944), Selected Works,  Vol. III, p. 165.

The way these comrades look at problems is wrong. They do not look at the essential or main aspects but emphasize the non-essential or minor ones. It should be pointed out that these non-essential or minor aspects must not be overlooked and must be dealt with one by one. But they should not be taken as the essential or main aspects, or we will lose our bearings.

On the Question of Agricultural Co-operation  (July 31, 1955), 3rd ed., pp. 17-18.

In this world, things are complicated and are decided by many factors. We should look at problems from different aspects, not from just one.

"On the Chungking Negotiations'' (October 17, 1945), Selected Works,  Vol. IV, p. 54.

Only those who are subjective, one-sided and superficial in their approach to problems will smugly issue orders or directives the moment they arrive on the scene, without considering the circumstances, without viewing things in their totality (their history and their present state as a whole) and without getting to the essence of things (their nature and the internal relations between one thing and another). Such people are bound to trip and fall.

"On Practice" (July 1937), Selected Works,  Vol. I, p. 302.

In studying a problem, we must shun subjectivity, one-sidedness and superficiality. To be subjective means not to look at problems objectively, that is, not to use the materialist viewpoint in looking at problems. I have discussed this in my essay "On Practice". To be one-sided means not to look at problems all-sidedly.... Or it may be called seeing the part but not the whole, seeing the trees but not the forest. That way it is impossible to find the method for resolving a contradiction, it is impossible to accomplish the tasks of the revolution, to carry out assignments well or to develop inner-Party ideological struggle correctly. When Sun Wu Tzu said in discussing military science, "Know the enemy and know yourself, and you can fight a hundred battles with no danger of defeat", he was referring to the two sides in a battle. Wei Cheng of the Tang Dynasty also understood the error of one-sidedness when he said, "Listen to both sides and you will be enlightened, heed only one side and you will be benighted." But our comrades often look at problems one-sidedly, and so they often run into snags. ... Lenin said:

... in order really to know an object we must embrace, study, all its sides, all connections and "mediations". We shall never achieve this completely, but the demand for all-sidedness is a safeguard against mistakes and rigidity.

We should remember his words. To be superficial means to consider neither the characteristics of a contradiction in its totality nor the characteristics of each of its aspects; it means to deny the necessity for probing deeply into a thing and minutely studying the characteristics of its contradiction, but instead merely to look from afar and, after glimpsing the rough outline, immediately to try to resolve the contradiction (to answer a question, settle a dispute, handle work, or direct a military operation). This way of doing things is bound to lead to trouble. ...To be one-sided and superficial is at the same time to be subjective. For all objective things are actually interconnected and are governed by inner laws, but, instead of undertaking the task of reflecting things as they really are, some people only look at things one-sidedly or superficially and know neither their interconnections nor their inner laws, and so their method is subjectivist.

"On Contradiction" (August 1937), Selected Works,  Vol. I, pp. 323-24.*

One-sidedness means thinking in terms of absolutes, that is, a metaphysical approach to problems. In the appraisal of our work, it is one-sided to regard everything either as all positive or as all negative. ... To regard everything as positive is to see only the good and not the bad, and to tolerate only praise and no criticism. To talk as though our work is good in every respect is at variance with the facts. It is not true that everything is good; there are still shortcomings and mistakes. But neither is it true that everything is bad, and that, too, is at variance with the facts. Here analysis is necessary. To negate everything is to think, without having made any analysis, that nothing has been done well and that the great work of socialist construction, the great struggle in which hundreds of millions of people are participating, is a complete mess with nothing in it worth commending. Although there is a difference between the many people who hold such views and those who are hostile to the socialist system, these views are very mistaken and harmful and can only dishearten people. It is wrong to appraise our work either from the viewpoint that everything is positive, or from the viewpoint that everything is negative.

Speech at the Chinese Communist Party's National Conference on Propaganda Work  (March 12, 1957), 1st pocket ed., pp. 16-17.*

In approaching a problem a Marxist should see the whole as well as the parts. A frog in a well says, "The sky is no bigger than the mouth of the well." That is untrue, for the sky is not just the size of the mouth of the well. If it said, "A part of the sky is the size of the mouth of a well", that would be true, for it tallies with the facts.

"On Tactics Against Japanese Imperialism" (December 27, 1935), Selected Works,  Vol. I, p. 159.

We must learn to look at problems allsidedly, seeing the reverse as well as the obverse side of things. In given conditions, a bad thing can lead to good results and a good thing to bad results.

On the Correct Handling of Contradictions Among the People  (February 27, 1957), 1st pocket ed., pp. 66-67.*

While we recognize that in the general development of history the material determines the mental and social being determines social consciousness, we also - and indeed must - recognize the reaction of mental on material things, of social consciousness on social being and of the superstructure on the economic base. This does not go against materialism; on the contrary, it avoids mechanical materialism and firmly upholds dialectical materialism.

"On Contradiction" (August 1937), Selected Works,  Vol. I, p. 336.*

In seeking victory, those who direct a war cannot overstep the limitations imposed by the objective conditions; within these limitations, however, they can and must play a dynamic role in striving for victory. The stage of action for commanders in a war must be built upon objective possibilities, but on that stage they can direct the performance of many a drama, full of sound and colour, power and grandeur.

"On Protracted War" (May 1938), Selected Works,  Vol. II, p. 152.

People must adapt their thinking to the changed conditions. Of course no one should go off into wild flights of fancy, or make plans of action unwarranted by the objective situation, or stretch for the impossible. The problem today, however, is that Rightist conservative thinking is still causing mischief in many spheres and preventing the work in these spheres from keeping pace with the development of the objective situation. The present problem is that many people consider it impossible to accomplish things which could be accomplished if they exerted themselves.

Preface to The Socialist Upsurge in China's Countryside  (December 27, 1955), Chinese ed., Vol. I.

We should always use our brains and think everything over carefully. A common saying goes, "Knit your brows and you will hit upon a stratagem." In other words much thinking yields wisdom. In order to get rid of the blindness which exists to a serious extent in our Party, we must encourage our comrades to think, to learn the method of analysis and to cultivate the habit of analysis.

"Our Study and the Current Situation" (April 12, 1944), Selected Works,  Vol. III, pp. 174-75.*

If in any process thete arc a number of contradictions, one of them must be the principal contradiction playing the leading and decisive role, while the rest occupy a secondary and subordinate position. Therefore, in studying any complex process in which there are two or more contradictions, we must devote every effort to finding its principal contradiction. Once this principal contradiction is grasped, all problems can be readily solved.

"On Contradiction" (August 1937), Selected Works,  Vol. I, p. 332.*

Of the two contradictory aspects, one must be principal and the other secondary. The principal aspect is the one playing the leading role in the contradiction. The nature of a thing is determined mainly by the principal aspect of a contradiction, the aspect which has gained the dominant position.

But this situation is not static; the principal and the non-principal aspects of a contradiction transform themselves into each other and the nature of the thing changes accordingly.

Ibid.,  p. 333.

It is not enough to set tasks, we must also solve the problem of the methods for carrying them out. If our task is to cross a river, we cannot cross it without a bridge or a boat. Unless the bridge or boat problem is solved, it is idle to speak of crossing the river. Unless the problem of method is solved, talk ahout the task is useless.

"Be Concerned with the Well-Being of the Masses, Pay Attention to Methods of Work" (January 27, 1934), Selected Works,  Vol. I, p. 150.

In any task, if no general and widespread call is issued, the broad masses cannot be mobilized for action. But if persons in leading positions confine themselves to a general call - if they do not personally, in some of the organizations, go deeply and concretely into the work called for, make a break-through at some single point, gain experience and use this experience for guiding other units - then they will have no way of testing the correctness or of enriching the content of their general call, and there is the danger that nothing may come of it.

"Some Questions Concerning Methods of Leadership" (June 1, 1943), Selected Works,  Vol. III, p. 117.

No one in a leading position is competent to give general guidance to all the units unless he derives concrete experience from particular individuals and events in particular subordinate units. This method must be promoted everywhere so that leading cadres at all levels learn to apply it.

Ibid.,  p. 118.

In any given place, there cannot be a number of central tasks at the same time. At any one time there can be only one central task, supplemented by other tasks of a second or third order of importance. Consequently, the person with over-all responsibility in the locality must take into account the history and circumstances of the struggle there and put the different tasks in their proper order; he should not act upon each instruction as it comes from the higher organization without any planning of his own, and thereby create a multitudc of "central tasks" and a state of confusion and disorder. Nor should a higher organization simultaneously assign many tasks to a lower organization without indicating their relative importance and urgency or without specifying which is central, for that will lead to confusion in the steps to be taken by the lower organizations in their work and thus no definite results will be achieved. It is part of the art of leadership to take the whole situation into account and plan accordingly in the light of the historical conditions and existing circumstances of each locality, decide correctly on the centre of gravity and the sequence of the work for each period, steadfastly carry through the decision, and make sure that definite results are achieved.

Ibid., p. 121.

It [a regional or sub-regional bureau of the Central Committee of the Party] should constantly have a grip on the progress of the work, exchange experience and correct mistakes; it should not wait several months, half a year or a year before holding summing-up meetings for a general check-up and a general correction of mistakes. Waiting leads to great loss, while correcting mistakes as soon as they occur reduces loss.

"On the Policy Concerning Industry and Commerce" (February 27, 1948), Selected Works,  Vol. IV, p. 204.

Don't wait until problems pile up and cause a lot of trouble before trying to solve them. Leaders must march ahead of the movement, not lag behind it.

Introductory note to "Contract on a Seasonal Basis" (I955), The Socialist Upsurge in China's Countryside,  Chinese ed., Vol. III.

What we need is an enthusiastic but calm state of mind and intense but orderly work.

"Problems of Strategy in China's Revolutionary War" (December 1936), Selected Works,  Vol. I, p. 211.