一切矛盾着的东西，互相联系着，不但在一定条件之下共处于一个统一体中，而且在一定条件之下互相转化，这就是矛盾的同一性的全部意义。列宁所谓“怎样成为同一的（怎样变成同一的），——在怎样的条件之下它们互相转化，成为同一的”，就是这个意思。 - Mao Zedong

Over a long period we have developed this concept for the struggle against the enemy: strategically we should despise all our enemies, but tactically we should take them all seriously. This also means that we must despise the enemy with respect to the whole, but that we must take him seriously with respect to each and every concrete question. If we do not despise the enemy with respect to the whole, we shall be committing the error of opportunism. Marx and Engels were only two individuals, and yet in those early days they already declared that capitalism would be overthrown throughout the world. But in dealing with concrete problems and particular enemies we shall be committing the error of adventurism unless we take them seriously. In war, battles can only be fought one by one and the enemy forces can only be destroyed one by one. Factories can only be built one by one. The peasants can only plow the land plot by plot. The same is even true of eating a meal. Strategically, we take the eating of a meal lightly—we know we can finish it. But actually we eat it mouthful by mouthful. It is impossible to swallow an entire banquet in one gulp. This is known as a piecemeal solution. In military parlance, it is called wiping out the enemy forces one by one.

As we have said, one must not treat all the contradictions in a process as being equal but must distinguish between the principal and the secondary contradictions, and pay special attention to grasping the principal one. But, in any given contradiction, whether principal or secondary, should the two contradictory aspects be treated as equal? Again, no. In any contradiction the development of the contradictory aspects is uneven. Sometimes they seem to be in equilibrium, which is however only temporary and relative, while unevenness is basic. 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.

My closest friend and brother – this world is lucky to have a great personality as Kim Il Sung. This causes my boundless happiness. The fate of the world revolution and the international communist movement are on your shoulders, Comrade Kim Il Sung. I wish you long life and good health.