“There isn't any fear in existence itself, or any uncertainty, but living creates it.”

Response to State of the Union speech http://www.cbsnews.com/8301-250_162-57569091/full-text-rubios-republican-response/,
2010s, 2013

The Dead Past (1956)

First speech of Tony Abbott to Australian Parliament https://parlinfo.aph.gov.au/parlInfo/search/display/display.w3p;query=Id:%22chamber/hansardr/1994-05-31/0043%22, 1994.
First speech to Parliament

Misattributed

Not by Twain, but from Edward Abbey's A Voice Crying In The Wilderness (1989).
Misattributed

Source: The Theater and Its Double

There is fear of what happened yesterday in relation to the possibility of its repetition tomorrow; there is always a fixed point from which relationship takes place. How does fear come into this? I had pain yesterday; there is the memory of it and I do not want it again tomorrow. Thinking about the pain of yesterday, thinking which involves the memory of yesterday’s pain, projects the fear of having pain again tomorrow. So it is thought that brings about fear. Thought breeds fear; thought also cultivates pleasure. To understand fear you must also understand pleasure — they are interrelated; without understanding one you cannot understand the other. This means that one cannot say ‘I must only have pleasure and no fear’; fear is the other side of the coin which is called pleasure. Thinking with the images of yesterday’s pleasure, thought imagines that you may not have that pleasure tomorrow; so thought engenders fear. Thought tries to sustain pleasure and thereby nourishes fear. Thought has separated itself as the analyzer and the thing to be analyzed; they are both parts of thought playing tricks upon itself. In doing all this it is refusing to examine the unconscious fears; it brings in time as a means of escaping fear and yet at the same time sustains fear.
Beyond Violence (1973), p. 66, ISBN 0-06-064839-2
1970s

Some Men are More Perfect Than Others (1973)

Towards a Systems Theory of Organization, 1985, From Data to Wisdom, 1989