“Membership in the social democracy means a struggle, a political struggle with grievous persecutions, and a private struggle for existence, a struggle that for the majority is far more difficult and heavy than the political struggle. And it is necessary, because the courage for this twofold struggle is created only by the consciousness that the injustice of society by which the great majority of mankind are to-day oppressed, corrupted and crippled, can only be abolished through a revolutionary movement, that is, a movement that shall completely exterminate capitalism with every fiber of its roots.”

Source: Essai de semantique, 1897, p. 104-5 ; as cited in: Schaff (1962:14).

Mutual Aid: A Factor of Evolution (1902)
Context: In the animal world we have seen that the vast majority of species live in societies, and that they find in association the best arms for the struggle for life: understood, of course, in its wide Darwinian sense — not as a struggle for the sheer means of existence, but as a struggle against all natural conditions unfavourable to the species. The animal species, in which individual struggle has been reduced to its narrowest limits, and the practice of mutual aid has attained the greatest development, are invariably the most numerous, the most prosperous, and the most open to further progress. The mutual protection which is obtained in this case, the possibility of attaining old age and of accumulating experience, the higher intellectual development, and the further growth of sociable habits, secure the maintenance of the species, its extension, and its further progressive evolution. The unsociable species, on the contrary, are doomed to decay.

"The Commercial Motive" Christian Century 40 (Feb 22, 1923)

As quoted in Nikos Kazantzakis (1968) by Helen Kazantzakis, p. 507
Context: The major and almost only theme of all my work is the struggle of man with "God": the unyielding, inextinguishable struggle of the naked worm called "man" against the terrifying power and darkness of the forces within him and around him.

Source: How Europe Underdeveloped Africa (1972), p. 205.
Context: But what is relevant here is to understand why a Shaka was possible in Africa in the nineteenth century, before the coming of colonial rule. Had Shaka been a slave to some cotton planter in Mississippi or some sugar planter in Jamaica, he might have had an ear or a hand chopped off for being a “recalcitrant nigger,” or at best he might have distinguished himself in leading a slave revolt. For the only great men among the unfree and the oppressed are those who struggle to destroy the oppressor. On a slave plantation, Shaka would not have built a Zulu army and a Zulu state—that much is certain. Nor could any African build anything during the colonial period, however much a genius he may have been. As it was, Shaka was a herdsman and a warrior. As a youth, he tended cattle on the open plains—free to develop his own potential and apply it to his environment. Shaka was able to invest his talents and creative energies in a worthwhile endeavor of construction. He was not concerned with fighting for or against slave traders; he was not concerned with the problem of how to resell goods made in Sweden and France. He was concerned with how to develop the Zulu area within the limits imposed by his people’s resources. It must be recognized that things such as military techniques were responses to real needs, that the work of the individual originates in and is backed by the action of society as a whole, and that whatever was achieved by any one leader must have been bounded by historical circumstances and the level of development, which determine the extent to which an individual can first discover, then augment, and then display his potential.

Introduction
The Female Eunuch (1970)
Context: With them she can discover cooperation, sympathy and love. The end cannot justify the means: if she finds that her revolutionary way leads only to further discipline and continuing incomprehension, with their corollaries of bitterness and diminution, no matter how glittering the objective which would justify it, she must understand that it is a wrong way and an illusory end. The struggle which is not joyous is the wrong struggle. The joy of the struggle is not hedonism and hilarity, but the sense of purpose, achievement and dignity which is the reflowering of etiolated energy. Only these can sustain her and keep the flow of energy coming. The problems are only equalled by the possibilities: every mistake made is redeemed when it is understood. The only ways in which she can feel such joy are radical ones: the more derided and maligned the action that she undertakes, the more radical.

Source: On the Foreign Policy of the Soviet State

Source: The Diary of Frida Kahlo: An Intimate Self-Portrait

Address before the Indian Council of World Affairs, New Delhi, India, April 5, 1956, as quoted in Walter P Reuther: Selected Papers (1961), by Henry M. Christman, p. 131
1950s, Address before the Indian Council on World Affairs (1956)