“Socialism is a human ideal, an inevitable course of historical development, and therefore it is perfectly clear that socialism will rise again in the end.”

Source: A Theology of Liberation (1971), p. 54

Source: Anarcho-Syndicalism (1938), Ch. 1 "Anarchism: Its Aims and Purposes"
Context: Anarchism recognises only the relative significance of ideas, institutions, and social conditions. It is, therefore not a fixed, self enclosed social system, but rather a definite trend in the historical development of mankind, which, in contrast with the intellectual guardianship of all clerical and governmental institutions, strives for the free unhindered unfolding of all the individual and social forces in life. Even freedom is only a relative, not an absolute concept, since it tends constantly to broaden its scope and to affect wider circles in manifold ways. For the Anarchist, freedom is not an abstract philosophical concept, but the vital concrete possibility for every human being to bring to full development all capacities and talents with which nature has endowed him, and turn them to social account. The less this natural development of man is interfered with by ecclesiastical or political guardianship, the more efficient and harmonious will human personality become, the more will it become the measure of the intellectual culture of the society in which it has grown.

On Contradiction (1937)

Source: De architectura (The Ten Books On Architecture) (~ 15BC), Book II, Chapter I, Sec. 2

Free Synagogue Pulpit: Sermons and Addresses
Source: p. 28 https://archive.org/details/freesynagoguepu00wisegoog/page/n36/mode/2up

Source: Nationalism and Culture (1937), Ch. 1 "The Insufficiency of Economic Materialism"
Context: Every process which arises from our physical being and is related to it, is an event which lies outside of our volition. Every social process, however, arises from human intentions and human goal setting and occurs within the limits of our volition. Consequently, it is not subject to the concept of natural necessity. … We are here stating no prejudiced opinion, but merely an established fact. Every result of human purposiveness is of indisputable importance for man's social existence, but we should stop regarding social processes as deterministic manifestations of a necessary course of events. Such a view can only lead to the most erroneous conclusions and contribute to a fatal confusion in our understanding of historical events.
It is doubtless the task of the historian to trace the inner connection of historical events and to make clear their causes and effects, but he must not forget that these connections are of a sort quite different from those of natural physical events and must therefore have quite a different valuation.

Letter (19 December 1885), sent by Conrad from Calcutta to Joseph Spiridion in England, quoted in: [Najder, Zdzisław, Joseph Conrad: A Life, 106, https://books.google.com/books?id=F8ANmy_7mTMC&pg=PA106, 2007, Camden House, 978-1-57113-347-2]

Source: Economic Heresies (1971), Chapter IV, Increasing and Diminishing Returns, p. 63

Source: Democracy for the Few (2010 [1974]), sixth edition, Chapter 17, p. 334