Source: The Perfectibility of Man (1971), p. 282.
Quotes about doubt
page 18

Wonderful Baby
Song lyrics, Homeless Brother (1974)

“Kill your doubt with the coldest of weapons: Confidence.”
Lyrics, Light Grenades (2006)
Excerpt from a dedication to an unpublished short story, "First Squad, First Platoon"; from Serling to his as yet unborn children.
Other

17 U.S. (4 Wheaton) 316, 405
McCulloch v. Maryland (1819)

The Unconscious and Repetition
The Four Fundamental Concepts of Psycho Analysis (1978)
Source: Darwin, God and the Meaning of Life: How Evolutionary Theory Undermines Everything You Think You Know (2010), p. 287

God doesn't believe in atheists (2002)

U.S. supports "terrorists", Iranian speaker says http://www.reuters.com/article/politicsNews/idUSISL21727120070405 Apr 5, 2007 http://english.aljazeera.net/NR/exeres/753B743D-1980-47C6-A64C-625DD11B48A2.htm

"The Substitutes for Religion, The Religion of Sex"
Proper Studies (1927)

Interview http://web.archive.org/web/20130614041959/http://www.youtube.com/watch?v=33oIF-ggK5U (2013).
2011 - 2015

Eden to President Eisenhower (1 October 1956), quoted in Scott Lucas, Britain and Suez (Manchester University Press, 1996), p. 69

1920s, Ordered Liberty and World Peace (1924)

Great Books: The Foundation of a Liberal Education (1954)

As quoted in The Alternative Leadership 1936-1941 (1996) by Aleander Werth p. 63

"The Legacy of Ratu Sir Kamisese Mara" - Memorial Lecture http://www.flp.org.fj/s030827.htm, Waterfront Hotel, Lautoka, 27 August 2003

The Tragic Sense of Life (1913), XI : The Practical Problem

Source: A Man of Law's Tale (1952), At the Scottish bar, p. 86

Love, Hope and Beauty
The Improvisatrice (1824)

Source: Presidential Address British Association for the Advancement of Science, Section A (1910), p. 290. ; Cited in: Moritz (1914, 184): Mathematics as a fine art.
Comments on Japan, 7 October 2002

Senate Foreign Relations Committee Hearing On U.S Foreign Policy in Iraq http://www.feingold.senate.gov/statements/05/10/20051019SFRC.html, October 19, 2005.

Speech https://api.parliament.uk/historic-hansard/commons/1938/oct/05/policy-of-his-majestys-government#column_370 in the House of Commons (5 October 1938) against the Munich Agreement
The 1930s

“Doubt must be no more than vigilance, otherwise it can become dangerous.”
F 53
Aphorisms (1765-1799), Notebook F (1776-1779)

Variant: Nature shows us only the tail of the lion. But I do not doubt that the lion belongs to it even though he cannot at once reveal himself because of his enormous size.
As quoted by Abraham Pais in Subtle is the Lord:The Science and Life of Albert Einstein (1982), p. 235 ISBN 0-192-80672-6
Source: Letter to Heinrich Zangger (10 March 1914), quoted in The Curious History of Relativity by Jean Eisenstaedt (2006), p. 126 http://books.google.com/books?id=d2bnXTOtCD8C&lpg=PP1&pg=PA126#v=onepage&q&f=false.

"American Facts" in Life Without and Life Within (1860) edited by Arthur Buckminster Fuller, p. 108.

On the loss of some of his brothers, in a letter to his brother John, as quoted in William the Silent (1897) by Frederic Harrison, p. 76
Source: The Testament of Jessie Lamb (2011), Chapter 1 (p. 6)
Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 422.

The Friedrich Hayek I knew, and what he got right - and wrong (2015)
Source: The Managerial Revolution, 1941, p. 201–202.

Source: "What Is an Administrator?" 1936, p. 6 ; As cited in Albert Lepawsky (1949), Administration, p. 658

Source: Translations, The Tale of Genji (1925–1933), Ch. 19: 'A Wreath of Cloud'

The Education of Henry Adams (1907)

Speech http://hansard.millbanksystems.com/commons/1986/nov/06/economic-policy in the House of Commons (6 November 1986)
1980s
Source: Finding Our Way: Leadership For an Uncertain Time (2005), p. 327

From, Light on Carmel: An Anthology from the Works of Brother John of Saint Samson, O.Carm.

2000s, 2002, Compassionate Conservatism (April 2002)

Examples of self-translation (c. 2004), Quotes - Zitate - Citations - Citazioni

Speech in the House of Commons (3 February 1808) on the British bombardment of Copenhagen, quoted in George Henry Francis, Opinions and Policy of the Right Honourable Viscount Palmerston, G.C.B., M.P., &c. as Minister, Diplomatist, and Statesman, During More Than Forty Years of Public Life (London: Colburn and Co., 1852), pp. 1-3.
1800s

“Attempt the end, and never stand to doubt;
Nothing's so hard but search will find it out.”
"Seek and Find". Compare: "Nil tam difficilest quin quærendo investigari possiet" (transalted as "Nothing is so difficult but that it may be found out by seeking"), Terence, Heautontimoroumenos, iv. 2, 8.
Hesperides (1648)

C. S. Lewis, letter to Arthur Greeves dated October 1, 1934, cited from W. H. Lewis (ed.) The Collected Letters of C. S. Lewis (San Francisco: HarperSanFrancisco, 2004) vol. 2, p. 143
Criticism

Choice
The Note-Books of Samuel Butler (1912), Part XX - First Principles
The Roots of Anticapitalism

Source: Don't Start the Revolution Without Me! (2008), Ch. 11 (p. 212)

What Made America Famous?
Song lyrics, Verities & Balderdash (1974)

Hugo Chávez during his closing speech at the World Social Forum in Porto Alegre, Brazil. January 31, 2005. http://www.venezuelanalysis.com/news.php?newsno=1486
2005
Source: The Probability Pad (1970), Chapter 16 (p. 125)

On her actual technique of training, in "On Gangubai Hangal by Sabina Sehgal Computer Science & Engineering - University of Washington".

Cross-correspondences (p. 68)
The Immortalization Commission: The Strange Quest to Cheat Death (2011)

Peter Cushing Interview 1973 http://www.bbc.co.uk/programmes/p048plh0 (1973)

At the Nuremberg Trials. Quoted in "Valhalla's Warriors: A History of the Waffen SS on the Eastern Front" - Page 186 - by Terry Goldsworthy - History - 2007.
We nominated Jeremy Corbyn for the leadership. Now we regret it (6 May 2016)

[Swami Tapasyananda, Swami Nikhilananda, Sri Sarada Devi, the Holy Mother; Life and Conversations, 361]

1920s, Toleration and Liberalism (1925)

Progress, Coexistence and Intellectual Freedom (1968), Dangers, The Threat to Intellectual Freedom
All and Everything: Meetings with Remarkable Men (1963)

Source: The Philosopher's Apprentice (2008), Chapter 13 (p. 292)
Top Lebanese Sunni Cleric Fathi Yakan: Bin Laden a Man After My Own Heart; I Am Not Sad Because of 9/11 and I Have Never Condemned this Attack, MEMRI, March 2007 http://www.memritv.org/clip_transcript/en/1408.htm,

“There is no doubt that life is given us, not to be enjoyed, but to be overcome — to be got over.”
Allerdings ist das Leben nicht eigentlich da, um genossen, sondern um überstanden, abgethan zu werden...
Parerga and Paralipomena (1851), Counsels and Maxims

Entertaining Angels
The Note-Books of Samuel Butler (1912), Part X - The Position of a HomoUnius Libri

Source: 1860s, Evidence as to Man's Place in Nature (1863), Ch.2, p. 126

As quoted in Modern Mathematicians, (1995) by Harry Henderson. ~ ISBN 0816032351

Vilem Flusser, Aspects and Prospects of Tsai's Work, Art International, March 1974

Concerning Operation Market Garden in his autobiography, 'The Memoirs of Field Marshal Montgomery' (1958)

p, 125
"On the Harmony of Theory and Practice in Mechanics" (Jan. 3, 1856)

On the occasion of the opening of Industrial and Arts Exhibition on 26 December 1903 in Madras (now known as Chennai) Modern_Mysore, Dr. B. R. Ambedkar Open University, 26 November 2013, archive.org, 203 http://archive.org/stream/modernmysore035292mbp/modernmysore035292mbp_djvu.txt,
As ruler of the state
Source: The Passionate Life (1983), p. 84

The New Day: Campaign Speeches of Herbert Hoover (1928)

Miss Manners' Guide to Excruciatingly Correct Behavior

Source: 1930s, A Dynamic Theory of Personality, 1935, p. v-vi.