Aspect Quotes - page 40
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.
Mao Zedong