Cute quotes

'Where Do We Go From Here?" as published in Where Do We Go from Here : Chaos or Community? (1967), p. 62; many statements in this book, or slight variants of them, were also part of his address Where Do We Go From Here?" which has a section below. A common variant appearing at least as early as 1968 has "Returning violence for violence multiplies violence..." An early version of the speech as published in A Martin Luther King Treasury (1964), p. 173, has : "Returning hate for hate multiplies hate..."
1960s
Source: A Testament of Hope: The Essential Writings and Speeches
Context: The ultimate weakness of violence is that it is a descending spiral, begetting the very thing it seeks to destroy. Instead of diminishing evil, it multiplies it. Through violence you may murder the liar, but you cannot murder the lie, nor establish the truth. Through violence you may murder the hater, but you do not murder hate. In fact, violence merely increases hate. So it goes. … Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness: only light can do that. Hate cannot drive out hate: only love can do that.

Variant: Whatever our souls are made of, his and mine are the same
Source: Wuthering Heights

Variant: Imperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.

"In Search of a Majority: An Address" (Feb 1960); reprinted in Baldwin, "Nobody Knows My Name: More Notes of a Native Son" https://en.wikipedia.org/wiki/Nobody_Knows_My_Name (1961)

Variant: You know you're in love when you can't fall asleep because reality is finally better than your dreams.

Variant: I love you as one loves certain dark things, secretly, between the shadow and the soul.
Source: 100 Love Sonnets

As quoted in Journal of France and Germany (1942–1944) by Gilbert Fowler White, in excerpt published in Living with Nature's Extremes: The Life of Gilbert Fowler White (2006) by Robert E. Hinshaw, p. 62. From the context http://books.google.com/books?id=_2qfZRp9SeEC&lpg=PP1&pg=PA62#v=onepage&q&f=false it seems that White did not specify whether he had heard Einstein himself say this or whether he was repeating a quote that had been passed along by someone else, so without a primary source the validity of this quote should be considered questionable.
Some have argued that elsewhere Einstein defined a "miracle" as a type of event he did not believe was possible—Einstein on Religion by Max Jammer (1999) quotes on p. 89 from a 1931 conversation Einstein had with David Reichinstein, where Reichinstein brought up philosopher Arthur Liebert's argument that the indeterminism of quantum mechanics might allow for the possibility of miracles, and Einstein replied that Liebert's argument dealt "with a domain in which lawful rationality [determinism] does not exist. A 'miracle,' however, is an exception from lawfulness; hence, there where lawfulness does not exist, also its exception, i.e., a miracle, cannot exist." ("Dort, wo eine Gesetzmässigkeit nicht vorhanden ist, kann auch ihre Ausnahme, d.h. ein Wunder, nicht existieren." D. Reichenstein, Die Religion der Gebildeten (1941), p. 21). However, it is clear from the context that Einstein was stating only that miracles cannot exist in a domain (quantum mechanics) where lawful rationality does not exist. He did not claim that miracles could never exist in any domain. Indeed, Einstein clearly believed, as seen in many quotations above, that the universe was comprehensible and rational, but he also described this characteristic of the universe as a "miracle". In another example, he is quoted as claiming belief in a God, "Who reveals Himself in the lawful harmony of the world."
As quoted in From Yale to Jail: The Life Story of a Moral Dissenter (1993) by David T. Dellinger, p. 418
Disputed
Variant: There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.
Variant: There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.

1960s, The Trumpet of Conscience (1967)
Variant: In the end, we will remember not the words of our enemies, but the silence of our friends.

Source: The Perks of Being a Wallflower

1979

Source: The Alchemist

Variant: The only remedy for love is to love more.

Often attributed to Churchill, this thought was originally expressed by the French author Victor Hugo in Villemain (1845), as follows: You have enemies? Why, it is the story of every man who has done a great deed or created a new idea. It is the cloud which thunders around everything that shines. Fame must have enemies, as light must have gnats. Do not bother yourself about it; disdain. Keep your mind serene as you keep your life clear.
Villemain is a brief segment taken from Hugo’s Choses Vues (Things Seen), a running journal Hugo kept of events he witnessed. The original French versions of these journals were published after Hugo's death.
Misattributed

We Bereaved (1929)

Source: book Man's Search For Meaning

As quoted in The Gospel According to Coco Chanel : Life Lessons from the World's Most Elegant Woman (2009) by Karen Karbo

Variant: Be a rainbow in somebody else's cloud.
Source: Letter to My Daughter

Mildred Pierce

Source: Revolutionary Petunias

Source: Doctor Sleep

Source: The Book Thief

Variant: You can make more friends in two months by being interested in them, than in two years by making them interested in you.
Source: How to Win Friends and Influence People (1936), p. 52 (in 1998 edition)

Source: Going Bovine

Source: The Last Olympian

Attributed quotes

This Business of Living (1935-1950)

Source: Lolita

Variant: Life is not the breaths you take but the moments that take your breath away.

Source: Eat, pray, love: one woman's search for everything

Frequently misattributed to Marilyn Monroe or Kurt Cobain.
Source: https://books.google.com/books?id=xUtdDnEhkMMC&pg=PT12&lpg=PT12#v=onepage&q&f=false
Source: Autumn Leaves, Philosophical eLibrary, 2012, (Feuillets d'automne, 1941, trans. Jeanine Parisier Plottel)

Source: Journals of Ralph Waldo Emerson, with Annotations - 1841-1844

Variant: Walking with a friend in the dark is better than walking alone in the light.

The Bell (1958), ch. 19; 2001, p. 219.

Variant: Sometimes good things fall apart so that better things can fall together.

Red Cross Speech http://books.google.com/books?id=f6l-dsvnjhEC&pg=PA406&dq=%22Friendship+is+the+only+cement%22, New York (18 May 1918)
1910s

Source: The Diary of a Young Girl

Aphorism #33
Interglacial (2004)

Manuscript Found in Accra (2012), Love has always passed me by

Source: A Joseph Campbell Companion: Reflections on the Art of Living

Attributed to Kierkegaard in a number of books, the earliest located on Google Books being the 1976 book Jack Kerouac: Prophet of the New Romanticism by Robert A. Hipkiss, p. 83 http://books.google.com/books?id=g_JaAAAAMAAJ&q=%22problem+to+be+solved%22#search_anchor. In the 1948 The Hibbert Journal: Volumes 46-47 the quote is referred to as "the famous Kierkegaardian slogan" on p. 237 http://books.google.com/books?id=UuDRAAAAMAAJ&q=%22the+famous+Kierkegaardian+slogan+life+is+not+a+problem+to+be+solved%22#search_anchor, which may be intended to suggest the phrase is Kierkegaard-esque rather than being something written by Kierkegaard. In reality this seems to be a slightly altered version of the quote "The mystery of life is not a problem to be solved; it is a reality to be experienced" which appeared in the 1928 book The Conquest of Illusion by Jacobus Johannes Leeuw, p. 9 http://books.google.com/books?id=OFdVAAAAMAAJ&q=%22not+a+problem+to+be+solved%22#search_anchor.
Misattributed

Source: The Monk Who Sold His Ferrari

frequently attributed to Lennon, but entirely unsourced
Disputed

Quoted in: LIFE http://books.google.com/books?id=9EgEAAAAMBAJ&pg=PA9, Vol. 57, nr. 11 (11 September 1964). p. 9.
1960s

Jace to Clary, pg. 331
Variant: There is no pretending, I love you, and I will love you until I die, and if there is life after that, I'll love you then.
Source: The Mortal Instruments, City of Glass (2009)

Source: When You Come to a Fork in the Road, Take It!: Inspiration and Wisdom from One of Baseball's Greatest Heroes

Variant: You want my opinion? We're all a little weird. And life is a little weird. And when we find someone whose weirdness is compatible with ours, we join up with them and fall into mutually satisfying weirdness — and call it love — true love.
Source: True Love (1998)

Vol. I, ch. 14.
The Life of Sir William Osler (1925)

Source: Me: Stories of My Life

Without Love
Music, Slippery When Wet (1986)

Source: Wasted: A Memoir of Anorexia and Bulimia

Source: The Notebook

Remember, l. 13-14.
Source: Pre-Raphaelite Poetry: An Anthology

Source: Lord Arthur Savile's Crime and Other Stories

Source: You Can Heal Your Heart: Finding Peace After a Breakup, Divorce, or Death

As quoted in The Mammoth Book of Zingers, Quips, and One-Liners (2004) edited by Geoff Tibballs, p. 299
General sources

Variant: I love her, and that's the beginning and end of everything.
Source: Dear Scott, Dearest Zelda: The Love Letters of F. Scott and Zelda Fitzgerald

Source: Naruto, Vol. 01: The Tests of the Ninja

Disputed
Variant: No one can make you feel inferior without your permission.
Source: Sometimes claimed to appear in her book This is My Story, but in The Quote Verifier by Ralph Keyes (2006), Keyes writes on p. 97 that "Bartlett's and other sources say her famous quotation can be found in This is My Story, Roosevelt's 1937 autobiography. It can't. Quotographer Rosalie Maggio scoured that book and many others by and about Roosevelt in search of this line, without success. In their own extensive searching, archivists at the Franklin D. Roosevelt Library in Hyde Park, New York, have not been able to find the quotation in This Is My Story or any other writing by the First Lady. A discussion of some of the earliest known attributions of this quote to Roosevelt, which may be a paraphrase from an interview, can be found in this entry from Quote Investigator http://quoteinvestigator.com/2011/03/30/not-inferior/.

"Jubal Harshaw" in the first edition (1961); the later 1991 "Uncut" edition didn't have this line, because it was one Heinlein had added when he went through and trimmed the originally submitted manuscript on which the "Uncut" edition is based. Heinlein also later used a variant of this in The Cat Who Walks Through Walls where he has Xia quote Harshaw: "Dr. Harshaw says that 'the word "love" designates a subjective condition in which the welfare and happiness of another person are essential to one's own happiness.'"
Source: Stranger in a Strange Land (1961; 1991)