Historical experiences are worth noting. A line, a viewpoint, must be frequently and
repeatedly taught. It's not enough to limit it to a few; the broad revolutionary masses must
know it [1].

[1] This is a portion of Mao Zedong's speech at the Central Cultural Revolution Conference
on November 4, 1968. It was quoted in boldface in the editorial "Study the History of the
Two-Line Struggle Seriously" published in People's Daily, Red Flag, and Liberation Army Daily.
It appeared in the fifth issue of Red Flag, November 24, 1968, and in People's Daily and
Liberation Army Daily, November 25.