“I shall treat anarchism, despite its many variations: as a system of social thought, aiming at fundamental changes in the structure of society and particularly — for this is the common element uniting all its forms — at the replacement of the authoritarian state by some form of non-governmental cooperation between free individuals.”

Postscript (July 1973)
Anarchism : A History of Libertarian Ideas and Movements (1962)

Slavery and Freedom (1939), p. 147
Context: There is absolute truth in anarchism and it is to be seen in its attitude to the sovereignty of the state and to every form of state absolutism. … The religious truth of anarchism consists in this, that power over man is bound up with sin and evil, that a state of perfection is a state where there is no power of man over man, that is to say, anarchy. The Kingdom of God is freedom and the absence of such power... the Kingdom of God is anarchy.

Source: The Life of Poetry (1949), p. 96
Context: Belief has its structures, and its symbols change. Its tradition changes. All the relationships within these forms are inter-dependent. We look at the symbols, we hope to read them, we hope for sharing and communication. Sometimes it is there at once, we find it before the words arrive, as in the gesture of John Brown, or the communication of a great actor-dancer, whose gesture and attitude will tell us before his speech adds meaning from another source. Sometimes it rises in us sleeping, evoked by the images of dream, recognized in the blood. The buried voices carry a ground music; they have indeed lived the life of our people. In times of perversity and stress and sundering, it may be a life inverted, the poet who leaps from the ship into the sea; on the level of open belief, it will be the life of the tribe. In subjugated peoples, the poet emerges as prophet.

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.

Source: Sociology and modern systems theory (1967), p. 58.

The Book of Ammon
Context: Despite the popular idea of anarchists as violent men, Anarchism is the one non-violent social philosophy.… The function of the Anarchist is two-fold. By daily courage in non-cooperation with the tyrannical forces of the State and the Church, he helps to tear down present society; the Anarchist by daily cooperation with his fellows in overcoming evil with good-will and solidarity builds toward the anarchistic commonwealth which is formed by voluntary action with the right of secession.

Source: Leader of the Opposition (2009-2015), Battlelines book, (2013), p. 6.

Preface to the Third Edition (August 1942)
The Mass Psychology of Fascism (1933)

Source: Living systems, 1978, p. 16; As cited in: Sven Rasegård (2002) Man and Science: A Web of Systems and Social Conventions. p. 29