被敌人反对是好事而不是坏事

我认为，对我们来说，一个人，一个党，一个军队，或者一个学校，如若不被敌人反对，那就不好了那一定是同敌人同流合污了。如若被敌人反对，那就好了，那就证明我们同敌人划清界线了。如若敌人起劲地反对我们，把我们说得一塌糊涂，一无是处，那就更好了，那就证明我们不但同敌人划清了界线，而且证明我们的工作是很有成绩的了。　　　　　

——《被敌人反对是好事而不是坏事》（一九三九年五月二十六日）人民出版社版第二页

I hold that it is bad as far as we are concerned if a person, a political party, an army or a school is not attacked by the enemy, for in that case it would definitely mean that we have sunk to the level of the enemy. It is good if we are attacked by the enemy, since it proves that we have drawn a clear line of demarcation between the enemy and ourselves. It is even better if the enemy attacks us wildly and paints us as utterly black and without a single virtue; it demonstrates that we have not only drawn a clear line of demarcation between the enemy and ourselves but achieved a great deal in our work.

To be attacked by the enemy is not a bad thing but a good thing (May 26, 1939), first pocket ed., p. two.

http://www.marxists.org/reference/archive/mao/works/red-book/ch02.htm