“Then, does everyone lives in fear?'
The firelight barely reached the huge man standing beside Raskan, and the deep voice that came from that vague shape sounded loose, unguarded. 'I would say, most of the time, yes. Fear that our opinion might be chalanged. Fear that our way of seeing things might be called ignorant, self-serving, or indeed evil. Fear for our persons. Fear for our future, our fate. Our moment of death. Fear of failing in all that we set out to achieve. Fear of being forgotten.”

Source: Nation

The reference to Cassius is that of the character in William Shakespeare's play Julius Caesar. Listen to an mp3 sound file http://www.otr.com/murrow_mccarthy.shtml of parts of this statement.
See It Now (1954)
Context: No one familiar with the history of this country can deny that congressional committees are useful. It is necessary to investigate before legislating, but the line between investigating and persecuting is a very fine one and the junior Senator from Wisconsin has stepped over it repeatedly. His primary achievement has been in confusing the public mind as between the internal and the external threats of communism. We must not confuse dissent with disloyalty. We must remember always that accusation is not proof and that conviction depends upon evidence and due process of law. We will not walk in fear, one of another. We will not be driven by fear into an age of unreason, if we dig deep in our history and our doctrine, and remember that we are not descended from fearful men — not from men who feared to write, to speak, to associate and to defend causes that were, for the moment, unpopular. This is no time for men who oppose Senator McCarthy's methods to keep silent, or for those who approve. We can deny our heritage and our history, but we cannot escape responsibility for the result. There is no way for a citizen of a republic to abdicate his responsibilities. As a nation we have come into our full inheritance at a tender age. We proclaim ourselves, as indeed we are, the defenders of freedom, wherever it continues to exist in the world, but we cannot defend freedom abroad by deserting it at home. The actions of the junior Senator from Wisconsin have caused alarm and dismay amongst our allies abroad, and given considerable comfort to our enemies. And whose fault is that? Not really his. He didn't create this situation of fear; he merely exploited it — and rather successfully. Cassius was right. "The fault, dear Brutus, is not in our stars, but in ourselves." Good night, and good luck.

Jocasta (Line 977?).
Oedipus Rex
Variant: Nay, what should mortal fear, for whom the decrees of fortune are supreme and who hath clear foresight of nothing? 'Tis best to live at random, as one may.

E l' aspettar del male è mal peggiore
Forse, che non parrebbe il mal presente.
Canto I, stanza 82 (tr. Fairfax)
Gerusalemme Liberata (1581)

Source: The Myth of Male Power (1993), Part II: The Glass Cellars of the disposable sex, p. 142.

Source: A Return to Love: Reflections on the Principles of "A Course in Miracles" (1992), Ch. 7 : Work, §3 : Personal Power, p. 190 (p. 165 in some editions). This famous passage from her book is often erroneously attributed to Nelson Mandela. About the mis-attribution Williamson said, "Several years ago, this paragraph from A Return to Love began popping up everywhere, attributed to Nelson Mandela's 1994 inaugural address. As honored as I would be had President Mandela quoted my words, indeed he did not. I have no idea where that story came from, but I am gratified that the paragraph has come to mean so much to so many people."
Variant which appears in the film Coach Carter (2005): "Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure. It is our light, not our darkness that most frightens us. Your playing small does not serve the world. There is nothing enlightened about shrinking so that other people won't feel insecure around you. We are all meant to shine as children do. It's not just in some of us; it is in everyone. And as we let our own lights shine, we unconsciously give other people permission to do the same. As we are liberated from our own fear, our presence automatically liberates others."
Variant which appears in the film Akeelah and the Bee (2006), displayed in a picture frame on the wall, attributing it to Mandela: "Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure. We ask ourselves, Who am I to be brilliant, gorgeous, talented, fabulous? Actually, who are you not to be? We were born to make manifest the glory of God that is within us. And as we let our own light shine, we unconsciously give other people permission to do the same."
Context: Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure. It is our light, not our darkness that most frightens us. We ask ourselves, Who am I to be brilliant, gorgeous, talented, and fabulous? Actually, who are you not to be? You are a child of God. Your playing small does not serve the world. There is nothing enlightened about shrinking so that other people will not feel insecure around you. We are all meant to shine, as children do. We were born to make manifest the glory of God that is within us. It is not just in some of us; it is in everyone and as we let our own light shine, we unconsciously give others permission to do the same. As we are liberated from our own fear, our presence automatically liberates others.

1990s, Our March to Freedom is Irreversible (1990)
Context: Our march to freedom is irreversible. We must not allow fear to stand in our way. Universal suffrage on a common voters' roll in a united, democratic and non-racial South Africa is the only way to peace and racial harmony.

All Gall Is Divided (1952)