“Every difficulty slurred over will be a ghost to disturb your repose later on.”

A Narrative of Some of the Lord's Dealings with George Müller Written by Himself, Third Part.
Third Part of Narrative

Source: Promethea, Vol. 5

Original Sin
Song lyrics, Songs from the West Coast (2001)

This quote is commonly attributed to Churchill, but appears in the "Red Herrings: False Attributions" appendix of Churchill by Himself : The Definitive Collection of Quotations (2008) by Richard Langworth, without citation as to where it originates.
In American Character, a 1905 address by Brander Matthews, a similar quotation is attributed to L. P. Jacks ( link http://hdl.handle.net/2027/mdp.39015059451156?urlappend=%3Bseq=238).
""Our civilization is a perilous adventure for an uncertain prize... Human society is not a constructed thing but a human organization... We are adopting a false method of reform when we begin by operations that weaken society, either morally or materially, by lower its vitality, by plunging it into gloom and despair about itself, by inducing the atmosphere of the sick-room, and then when its courage and resources are at a low ebb, expecting it to perform some mighty feat of self-reformation... Social despair or bitterness does not get us anywhere... Low spirits are an intellectual luxury. An optimist is one who sees an opportunity in every difficulty. A pessimist is one who sees a difficulty in every opportunity... The conquest of great difficulties is the glory of human nature." L. P. Jacks, quoted in American character, by Brander Matthews, 1906
Misattributed
Variant: A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty.

Source: The Pale King (2011)

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 194.

Source: For One More Day

A misquote. It derives from an interview that journalist Bruce Cook conducted with Kerouac in 1968 and reported in his book The Beat Generation (1971). According to Cook, Kerouac explained to him his method of writing: "I'll just sit down and let it flow out of me ... It's the Holy Ghost that comes through you. You don't have to be a Catholic to know what I mean, and you don't have to be a Catholic for the Holy Ghost to speak through you." Source of misquote.

Neuromancer (1984)
Context: The lane to the land of the dead. Where you are, my friend. Marie-France, my lady, she prepared this road, but her lord choked her off before I could read the book of her days. Neuro from the nerves, the silver paths. Romancer. Necromancer. I call up the dead. But no, my friend," and the boy did a little dance, brown feet printing the sand, "I am the dead, and their land." He laughed. A gull cried, "Stay. If your woman is a ghost, she doesn't know it. Neither will you."