Depressing quotes
page 2

Variant: He was a Frenchman, a melancholy-looking man. His aspect was that of one who has been looking for the leak in a gas pipe with a lighted candle.
Source: The Man Upstairs and Other Stories
Misattributed

Hyperion http://www.gutenberg.org/etext/5436, Bk. III, Ch. IV (1839).
Variant: Believe me, every heart has its secret sorrows, which the world knows not, and oftentimes we call a man cold, when he is only sad.
Context: "Ah! this beautiful world!" said Flemming, with a smile. "Indeed, I know not what to think of it. Sometimes it is all gladness and sunshine, and Heaven itself lies not far off. And then it changes suddenly; and is dark and sorrowful, and clouds shut out the sky. In the lives of the saddest of us, there are bright days like this, when we feel as if we could take the great world in our arms and kiss it. Then come the gloomy hours, when the fire will neither burn on our hearths nor in our hearts; and all without and within is dismal, cold, and dark. Believe me, every heart has its secret sorrows, which the world knows not, and oftentimes we call a man cold, when he is only sad."

“The excursion is the same when you go looking for your sorrow as when you go looking for your joy.”
Source: For Darkness Shows the Stars

William James, "Is Life Worth Living?," The Will to Believe and Other Essays in Popular Philosophy (1897).
Misattributed
“Maybe you have to know darkness before you can appreciate the light.”
Source: A Ring of Endless Light (1980)
“Sometimes that's all you can do. Hope.”
Source: My Life in Black and White

“Concern should drive us into action, not into a depression.”

“The bitterest tears shed over graves are for words left unsaid and deeds left undone.”
Source: Little Foxes (1865), Ch. 3.
Source: Little Foxes: Or, the Insignificant Little Habits Which Mar Domestic Happiness

“What the caterpillar calls the end of the world, the master calls a butterfly.”
Source: Illusions: The Adventures of a Reluctant Messiah

“I thought the most beautiful thing in the world must be shadow.”
Source: The Bell Jar

As quoted in Visions : How Science Will Revolutionize the Twenty-First Century (1999) by Michio Kaku, p. 295
2000s and attributed from posthumous publications

Source: An Unquiet Mind: A Memoir of Moods and Madness

“Worry never robs tomorrow of its sorrow, it only saps today of its joy.”

“Death comes for us all. We can only choose how to face it when it comes.”
Aviendha
(15 October 1991)
Source: The Dragon Reborn

“To have felt too much is to end in feeling nothing.”
A comment regarding her divorce from Sinclair Lewis, quoted by Vincent Sheean in Dorothy and Red (1963)

“Either you will be you or you will not be at all.”
“The Knight,” p. 81
The Sun Watches the Sun (1999), Sequence: “What After”
The Complete Neurotic's Notebook (1981), Unclassified

“The love that lasts longest is the love that is never returned.”
Source: A Writer's Notebook (1946), p. 13

Mister Rogers' Neighborhood: Thoughts For All Ages http://pbskids.org/rogers/all_ages/thoughts1.htm

“If you want to conquer the anxiety of life, live in the moment, live in the breath.”
OM Chanting and Meditation (2010) http://books.google.co.uk/books/about/OM_Chanting_and_Meditation.html?id=3KKjPoFmf4YC,

“Concern should drive us into action and not into a depression.”
The Collected Works of Karen Horney (1957) by Karen Horney, p. 154: "We may feel genuinely concerned about world conditions, though such a concern should drive us into action and not into a depression."
Misattributed

“None are more hopelessly enslaved than those who falsely believe they are free.”
Niemand ist mehr Sklave, als der sich für frei hält, ohne es zu sein.
Bk. II, Ch. 5; source: Die Wahlverwandtschaften, Hamburger Ausgabe, Bd. 6 (Romane und Novellen I), dtv Verlag, München, 1982, p. 397 (II.5)
Elective Affinities (1809)

Voices in the Wilderness The Guardian (Saturday 28 September 2002).

Statement of 1937 or earlier, as quoted in The New Speaker's Treasury of Wit and Wisdom (1958) edited by Herbert Victor Prochnow
Context: Rebellion against your handicaps gets you nowhere. Self-pity gets you nowhere. One must have the adventurous daring to accept oneself as a bundle of possibilities and undertake the most interesting game in the world — making the most of one's best.

“For of all sad words of tongue or pen,
The saddest are these: "It might have been!"”
Bret Harte wrote a famous parody of this famous poem, "Mrs. Judge Jenkins" in which the Judge marries Maud, and which he ends with the lines:
Maud soon thought the Judge a bore,
With all his learning and all his lore;
And the Judge would have bartered Maud's fair face
For more refinement and social grace.
If, of all words of tongue and pen,
The saddest are, "It might have been,"
More sad are these we daily see:
"It is, but hadn't ought to be".
Maud Muller (1856)
Context: Alas for maiden, alas for Judge,
For rich repiner and household drudge!
God pity them both! and pity us all,
Who vainly the dreams of youth recall;
For of all sad words of tongue or pen,
The saddest are these: "It might have been!"
“But these are the people who never get it.”
"I want everything" http://home.earthlink.net/~2lulah2/everything.htm in What I Want from Life (1934) edited by Edmund George Cousins, p. 108
Context: I don’t know what I want.
Nobody knows — or if they do, they don’t know for long. I mean, you don’t want the same thing long enough for it to be What You Want From Life in capital letters.
Well, maybe some people do. Maybe there's a few simple folks — or maybe a few million, I don't know — who fix their hearts, and their minds, and their everlasting souls on a thing, and keep on all their lives hoping for it. Living for it. Wanting It From Life.
But these are the people who never get it.

“To be young is all there is in the world.”
Letter to his future wife Elsie Moll Kachel (21 March 1907); as published in Letters of Wallace Stevens (1966) edited by Holly Stevens, Ch. 5
Context: To be young is all there is in the world. The rest is nonsense — and cant. They talk so beautifully about work and having a family and a home (and I do, too, sometimes) — but it’s all worry and head-aches and respectable poverty and forced gushing.... Telling people how nice it is, when, in reality, you would give all of your last thirty years for one of your first thirty. Old people are tremendous frauds.

“And you do not think that this is possible?”
“I’ll believe in anything when I see evidence for it.”
Chapter 12 (p. 188)
Terminal World (2010)

“To be and not to be, that is the answer.”
This witticism derived from William Shakespeare's line "To be or not to be; that is the question" in Hamlet, has sometimes been attributed to Hein, but also to many others. The earliest occurrence so far located in research for Wikiquote was published in A Calendar of Doubts and Faiths (1930) by William Marias Malisoff.
Misattributed

“If you change the way you look at things, the things you look at change.”

“Is the thought that shapes the world.”
Original: (it) È il pensiero a dare forma al mondo.
Source: prevale.net