„Sarcasm is the last refuge of the imaginatively bankrupt.“

„Imagination is the beginning of creation. You imagine what you desire; you will what you imagine; and at last you create what you will.“

—  George Bernard Shaw Irish playwright 1856 - 1950

The Serpent, in Pt. I, Act I
1920s, Back to Methuselah (1921)

„Facts are the soil from which the story grows. Imagination is a last resort.“

—  Dorothy Dunnett British writer 1923 - 2001

„His last thought, as sleep overtook him, was that it was true what Cosimo had said: the universe was far stranger than anyone imagined, or could imagine.“

—  Stephen R. Lawhead American writer 1950

Source: The Bone House (2011), p. 56

„The basis of action is lack of imagination. It is the last resource of those who know not how to dream.“

—  Oscar Wilde Irish writer and poet 1854 - 1900

The Critic as Artist (1891), Part I
Variant: Action... is the last resource of those who know not how to dream.

„He realized that he had thought only about the first step, never imagined the last.“

—  Colum McCann, book Let the Great World Spin

Source: Let the Great World Spin

„What captured the heart and soul of the discerning listener was his uncanny craftiness and skill, the unfailing imaginative flights, rhythmic continuity and singular charm, making their lasting impact.“

—  Bhimsen Joshi Indian vocalist 1922 - 2011

Critique

„When in your last hour (think of this) all faculty in the broken spirit shall fade away, and sink into inanity — imagination, thought, effort, enjoyment — then will the flower of belief, which blossoms even in the night, remain to refresh you with its fragrance in the last darkness.“

—  Jean Paul German novelist 1763 - 1825

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 238.

„When was the last time you set your mind to wandering beyond today to imagine a brighter tomorrow? Let your mind go, dream a little, and you might just discover that anything is possible.“

—  Don Soderquist 1934 - 2016

Don Soderquist “ The Wal-Mart Way: The Inside Story of the Success of the World's Largest Company https://books.google.com/books?id=mIxwVLXdyjQC&lpg=PR9&dq=Don%20Soderquist&pg=PR9#v=onepage&q=Don%20Soderquist&f=false, Thomas Nelson, April 2005, p. 107.
On Leading Well

„The new pornographers subvert this last, vital privacy; they do our imagining for us. They take away the words that were of the night and shout them over the roof-tops, making them hollow.“

—  George Steiner American writer 1929 - 2020

"Night Words," Encounter (October 1965).
Language and Silence: Essays 1958-1966 (1967)

„Gradually, over the last twenty years, the vacuum has turned out to be more unusual, more fluid, less empty, and less intangible than even Einstein could have imagined.“

—  John D. Barrow British scientist 1952

Preface
The Book of Nothing (2009)
Context: The spooky ether was persistent. It took an Einstein to remove it from the Universe.... Gradually, over the last twenty years, the vacuum has turned out to be more unusual, more fluid, less empty, and less intangible than even Einstein could have imagined. Its presence is felt on the very smallest and largest dimensions over which the forces of Nature act.

„But in the imagination anything goes that can be imagined, and the limit of the imagination is a totally human world.“

—  Northrop Frye Canadian literary critic and literary theorist 1912 - 1991

"Quotes", The Educated Imagination (1963), Talk 1: The Motive For Metaphor http://northropfrye-theeducatedimagination.blogspot.ca/2009/08/1-motive-for-metaphor.html
Context: At the level of ordinary consciousness the individual man is the centre of everything, surrounded on all sides by what he isn't. At the level of practical sense, or civilization, there's a human circumference, a little cultivated world with a human shape, fenced off from the jungle and inside the sea and the sky. But in the imagination anything goes that can be imagined, and the limit of the imagination is a totally human world.

„I like to imagine that, on the day after my last, my library and I will crumble together, so that even when I am no more I'll still be with my books.“

—  Alberto Manguel writer 1948

Source: The Library at Night

„To imagine a language is to imagine a form of life.“

—  Ludwig Wittgenstein Austrian-British philosopher 1889 - 1951

„Generations of Arabs have paid with their lives and their futures because of a set of illusions that had nothing to do with Israel; these illusions come from deep within the world that we Arabs have constructed for ourselves, a world built upon denial, bombast and imagined past glories, ideas that have since been exposed as bankrupt and dangerous to the future of young Arab men and women who set out in 2011, against all odds, to build a new order.“

—  Kanan Makiya American orientalist 1949

"The Arab Spring started in Iraq", The New York Times (April 6, 2013)

„One must imagine,
One must deeply imagine“

—  Denise Levertov Poet 1923 - 1997

Conversation in Moscow
Context: To serve the people,
one must write for the ideal reader. Only for the ideal reader.
And who or what is that ideal reader? God. One must imagine,
One must deeply imagine

„Fear comes with imagination, it’s a penalty, it’s the price of imagination.“

—  Thomas Harris, Red Dragon

Source: Red Dragon

„All human accomplishment has the same origin, identically. Imagination is a force of nature. Is this not enough to make a person full of ecstasy? Imagination, imagination, imagination. It converts to actual. It sustains, it alters, it redeems!“

—  Saul Bellow, book Henderson the Rain King

General sources
Source: Henderson the Rain King (1959) [Viking/Penguin, 1984, ISBN 0-140-07269-1], ch. XVIII, p. 271

„It is not a thing that you can imagine. It only is. After that, there can be no imagining.“

—  Jonathan Safran Foer, book Everything Is Illuminated

Source: Everything Is Illuminated

„Your imagination, my dear fellow, is worth more than you imagine.“

—  Louis Aragon French poet, novelist and editor 1897 - 1982