“Democracy means to rely on the masses, correctly follow the mass line. Hence to be successful, the movement against embezzlement, waste and bureaucracy must rely on the masses.”

On the Correct Handling of Contradictions Among the People

Source: The Revolution Betrayed (1936), p. 40 in Doubleday, Doran & Company edition (1937)

Source: On Coalition Government (1945)

Saving Ourselves From Self-Destruction (2004)
Context: We must abandon the unworkable notion that it is morally reprehensible for some countries to pursue weapons of mass destruction yet morally acceptable for others to rely on them for security — and indeed to continue to refine their capacities and postulate plans for their use.
Similarly, we must abandon the traditional approach of defining security in terms of boundaries — city walls, border patrols, racial and religious groupings. The global community has become irreversibly interdependent, with the constant movement of people, ideas, goods and resources. In such a world, we must combat terrorism with an infectious security culture that crosses borders — an inclusive approach to security based on solidarity and the value of human life. In such a world, weapons of mass destruction have no place.

"Manipulating Public Opinion", American Journal of Sociology 33 (May, 1928), p. 958–971

Section 7
The True Believer (1951), Part One: The Appeal of Mass Movements
Context: There is a fundamental difference between the appeal of a mass movement and the appeal of a practical organization. The practical organization offers opportunities for self-advancement, and its appeal is mainly to self-interest. On the other hand, a mass movement, particularly in its active, revivalist phase, appeals not to those intent on bolstering and advancing a cherished self, but to those who crave to be rid of an unwanted self. A mass movement attracts and holds a following not because it can satisfy the desire for self-advancement, but because it can satisfy the passion for self-renunciation.

"Order reigns in Berlin", Last written words. Collected Works 4 <!-- p. 536 -->
Context: The leadership has failed. Even so, the leadership can and must be recreated from the masses and out of the masses. The masses are the decisive element, they are the rock on which the final victory of the revolution will be built. The masses were on the heights; they have developed this 'defeat' into one of the historical defeats which are the pride and strength of international socialism. And that is why the future victory will bloom from this 'defeat'.
'Order reigns in Berlin!' You stupid henchmen! Your 'order' is built on sand. Tomorrow the revolution will already 'raise itself with a rattle' and announce with fanfare, to your terror: I was, I am, I will be!

Quoted in "American Caesar: Douglas MacArthur" - by William Manchester - 1978 - Page 195