Quotes about matter
page 5
Source: The Awakening

“What's happening is merely what's happening. How you feel about it is another matter.”
Source: Conversations with God: An Uncommon Dialogue, Book 1

“No matter how big or soft or warm your bed is, you still have to get out of it.”

Letter to George Bainton, 15 October 1888, solicited for and printed in George Bainton, The Art of Authorship: Literary Reminiscences, Methods of Work, and Advice to Young Beginners (1890), pp. 87–88 http://books.google.com/books?id=XjBjzRN71_IC&pg=PA87.
Twain repeated the lightning bug/lightning comparison in several contexts, and credited Josh Billings for the idea:
Josh Billings defined the difference between humor and wit as that between the lightning bug and the lightning.
Speech at the 145th annual dinner of St. Andrew's Society, New York, 30 November 1901, Mark Twain Speaking (1976), ed. Paul Fatout, p. 424
Billings' original wording was characteristically affected:
Don't mistake vivacity for wit, thare iz about az mutch difference az thare iz between lightning and a lightning bug.
Josh Billings' Old Farmer's Allminax, "January 1871" http://books.google.com/books?id=sUI1AAAAMAAJ&pg=PT30. Also in Everybody's Friend, or; Josh Billing's Encyclopedia and Proverbial Philosophy of Wit and Humor (1874), p. 304 http://books.google.com/books?id=7rA8AAAAYAAJ&pg=PA304
Source: The Wit and Wisdom of Mark Twain

“To be without love is to be without grace, what matters most in life.
We is so much better than I.”
Source: Suzanne's Diary for Nicholas

“We have the right to lie, but not about the heart of the matter.”

Quoted in 'Tesla, 75, Predicts New Power Source', New York Times (5 Jul 1931), Section 2, 1.

Lufkin, Texas http://www.kidbrothers.net/words/concert-transcripts/lufkin-texas-jul1997-full.html (July 19, 1997)
In Concert

“What was observed by us in the third place is the nature or matter of the Milky Way itself, which, with the aid of the spyglass, may be observed so well that all the disputes that for so many generations have vexed philosophers are destroyed by visible certainty, and we are liberated from wordy arguments.”
Quòd tertio loco à nobis fuit obſeruatum, eſt ipſiuſmet LACTEI Circuli eſſentia, ſeu materies, quam Perſpicilli beneficio adeò ad ſenſum licet intueri, vt & altercationes omnes, quæ per tot ſæcula Philoſophos excrucia runt ab oculata certitudine dirimantur, nosque à verboſis dſputationibus liberemur.
Original text as reproduced in Edward Tufte, Beautiful Evidence (Cheshire, Connecticut: Graphics Press LLC, 2006), 101 (p. 3 of 4, insert between pp. 16V & 17R. Original manuscript renders the "q" in "nosque" with acute accent.)
Translation by Albert Van Helden in Sidereus Nuncius (Chicago, 1989), 62
Sidereus Nuncius (Venice, 1609)

2014, Remarks to the People of Estonia (September 2014)

Other

The Beginning of Time (1996)

An interview on a Granada Television chat-show, hosted by Shelley Rohde on Wednesday 20th of May 1981

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 464.

Letter to Natalie H. Wooley (2 May 1936), in Selected Letters V, 1934-1937 edited by August Derleth and Donald Wandrei, pp. 240-241
Non-Fiction, Letters

The New Economics for Industry, Government, Education (1993)

Alex Jones on Piers Morgan Tonight http://edition.cnn.com/TRANSCRIPTS/1301/12/pmt.01.html debating gun control, CNN, 7 January 2013 ( video http://www.youtube.com/watch?v=_XZvMwcluEg).
2013

Source: Crystallizing Public Opinion (1923), p. 171

Jerome Robbins in Heeley, David, producer and director. Fred Astaire: Puttin' on his Top Hat and Fred Astaire: Change Partners and Dance (two television programs written by John L. Miller), PBS, March 1980. (M).

2017, Farewell Address (January 2017)

Source: "The Place of Science in Modern Civilization", 1906, p. 355

XXXIX, 22, p. 172
‘The Second Part’, Chapters IV-XLI

Letter to his wife, reprinted in Rilke’s Letters on Cézanne (1952, trans. 1985). (October 21, 1907)
Rilke's Letters

The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.

Original: 如果戰端一開,就是地無分南北,年無分老幼,無論何人,皆有守土抗戰之責任,皆應抱定犧牲一切之決心!
蔣介石廬山《應戰宣言》

Homilies on the Gospel of Saint John http://www.ccel.org/ccel/schaff/npnf114.iv.lxxxiii.html, Homily LXXXI

Royal Institution Lecture (April 30, 1897) as quoted by Edmund Taylor Whittaker, A History of the Theories of Aether and Electricity from the Age of Descartes to the Close of the Nineteenth Century http://books.google.com/books?id=CGJDAAAAIAAJ (1910).
Quotes eat me

“It is ill to praise, and worse to reprimand in matters that you do not understand.”
The Notebooks of Leonardo da Vinci (1883), XIX Philosophical Maxims. Morals. Polemics and Speculations.
Variant: You do ill if you praise, and still worse if you reprove in a matter you do not understand.

Source: Reflections and Maxims (1746), p. 176.

To which may be replied,
1770s, African Slavery in America (March 1775)

Sharon Turner (1828) The History of England from the Earliest Period to the Death of Elizabeth, Longman, Rees, Orme, Brown and Green.

Source: 1910s, Our Knowledge of the External World (1914), p. 8

Source: 1950s, Portraits from Memory and Other Essays (1956), p. 211

Source: Kulturphilosophie (1923), Vol. 2 : Civilization and Ethics, Chapter 26

“Nobody wants to see us together, but it don't matter. No, because I got you babe.”
Don't Matter
Song lyrics, Konvicted (2006)

“Hear oh hear, if my prayer be worthy and such as you yourself might whisper to my frenzy. Those I begot (no matter in what bed) did not try to guide me, bereft of sight and sceptre, or sway my grieving with words. Nay behold (ah agony!), in their pride, kings this while by my calamity, they even mock my darkness, impatient of their father's groans. Even to them am I unclean? And does the sire of the gods see it and do naught? Do you at least, my rightful champion, come hither and range all my progeny for punishment. Put on your head this gore-soaked diadem that I tore off with my bloody nails. Spurred by a father's prayers, go against the brothers, go between them, let steel make partnership of blood fly asunder. Queen of Tartarus' pit, grant the wickedness I would fain see.”
Exaudi, si digna precor quaeque ipsa furenti
subiceres. orbum visu regnisque carentem
non regere aut dictis maerentem flectere adorti,
quos genui quocumque toro; quin ecce superbi
—pro dolor!—et nostro jamdudum funere reges
insultant tenebris gemitusque odere paternos.
hisne etiam funestus ego? et videt ista deorum
ignavus genitor? tu saltem debita vindex
huc ades et totos in poenam ordire nepotes.
indue quod madidum tabo diadema cruentis
unguibus abripui, votisque instincta paternis
i media in fratres, generis consortia ferro
dissiliant. da, Tartarei regina barathri,
quod cupiam vidisse nefas.
Source: Thebaid, Book I, Line 73

Plunkitt of Tammany Hall, Chapter 1, Honest Graft and Dishonest Graft

“The truth of the matter is that you always know the right thing to do. The hard part is doing it.”
Also attributed to Robert H. Schuller

Letter to Clark Ashton Smith (7 November 1930), in Selected Letters III, 1929-1931 edited by August Derleth and Donald Wandrei, p. 214
Non-Fiction, Letters

Letter to Edmund Halley (June 20, 1686) quoted in I. Bernard Cohen and George E. Smith, ed.s, The Cambridge Companion to Newton (2002) p. 204

Letter to Ottoline Morrell, January 30, 1916
1910s

Lord George Bentinck: A Political Biography (1852), p. 496.
1850s

“Human mind is capable of making up excuses to justify actions no matter how bad they were”

“War, no matter what our intentions may be, brings suffering and tragedy.”
Obama raises human rights in Vietnam, calls for 'peaceful resolution' of South China Sea disputes http://edition.cnn.com/2016/05/24/politics/obama-vietnam-south-china-sea/, CNN (24 May 2016)
2016

Interview with The Guardian (15 May 2011)

2013, Eulogy of Nelson Mandela (December 2013)
You Are An American http://psstpsstpsst1.blogspot.com/2005/08/you-are-american.html.

1910s, The Progressives, Past and Present (1910)

“Make sure that your religion is a matter between you and God only.”
Comment to Maurice O'Connor Drury, as quoted in Wittgenstein Reads Freud : The Myth of the Unconscious (1996) by Jacques Bouveresse, as translated by Carol Cosman, p. 14
Attributed from posthumous publications

"The Private Production of Defense" http://www.mises.org/journals/scholar/Hoppe.pdf (15 June 1999)

Sir Paul McCartney and PETA VP Dan Mathews Reflect on Two Decades of Activism http://www.peta.org/features/paul-mccartney-interview/ (April 2005)

[citation needed]
Others

As quoted in The Early Years of the Saturday Club, 1855-1870 (1918) by Edward Waldo Emerson.

1950s, What Desires Are Politically Important? (1950)

Letter https://books.google.it/books?id=-rgnCgAAQBAJ&pg=PT370 to Sidney G. Trist, Editor of the Animals' Friend Magazine, in his capacity as Secretary of the London Anti-Vivisection Society (26 May 1899), in Mark Twain's Notebooks, ed. Carlo De Vito (Black Dog & Leventhal, 2015)

Upon receiving discrepant accounts from the participants in a recent quarrel below his window.
Robert Chambers, Testimony: its Posture in the Scientific World http://books.google.com/books?id=pChcAAAAQAAJ& (1859) p. 12
Attributed

"Teaching and Thinking" in The Montreal Medical Journal (1895).

The Tomorrow Show with Tom Snyder (27th June 1980)

On World T20, "World T20: Joe Root challenges England squad to keep their cool in India" http://www.theguardian.com/sport/2016/mar/14/world-t20-england-india-mumbai, March 14, 2016. Steve Smith

Phaedrus, p. 47
L'Âme et la danse (1921)

1960 Letter from Reagan to Richard Nixon, As quoted in The New York Times (27 October 1984) http://www.nytimes.com/1984/10/27/us/on-the-record-text-of-1960-reagan-letter.html
1960s

Quote from Claude Monet par lui-meme – an interview by Thiébault-Sisson / translated by Louise McGlone Jacot-Descombes; published in 'Le Temps newspaper', 26 November 1900.
About Toulmouche, Monet first painting-teacher in Paris c. 1857
1900 - 1920

Quoted in "Simpson's contemporary quotations" - by James Beasley Simpson - Page 2