Fuck the faithful, fuck the committed, the dedicated, the true believers; fuck all the sure and certain people prepared to maim and kill whoever got in their way; fuck every cause that ended in murder and a child screaming.
Iain M Banks - Against A Dark Background
Considering the current situation, I couldn’t decide between two quotes, so, hopefully not against the rules, I shall post both.
When you fire that first shot, no matter how right you feel, you have no idea who’s going to die. You don’t know who’s children are going to scream and burn. How many hearts will be broken! How many lives shattered! How much blood will spill until everybody does what they’re always going to have to do from the very beginning – sit down and talk! Listen to me, listen. I just – I just want you to think. Do you know what thinking is? It’s just a fancy word for changing your mind.
- Twelfth Doctor, Doctor Who, Zygon Invasion.
So where do they come from?
From your fear…They come from the part that hates the Other, that will not change. They come from the sum of all your pettiness and stupidity and dullness. You fear tomorrow, and you’ve made your fear your god.
- Terry Pratchett, Monstrous Regiment
Reminds me a lot of the 1960s anti war posters that were take-offs of Douglas MacArthur’s 1951 speech.
Another variation:
Jade is to be treasured.
The jaded, not so much.
– MerelyGifted
Brilliant!
Certainly more than semi-precious. 
Fankyew, Dawling! So kind!
Is sharing an image ok? Have this over my home office desk and sent a copy to someone earlier this week who complained about how nothing works out they way they planed.
It’s really cool, and very true, but it’s not really a quotation, is it?
I’m not a prick: I wouldn’t dream of asking you to delete it or anything. 
Helmuth von Moltke 1800–91
Prussian military commander
- No plan of operations reaches with any certainty beyond the first encounter with the enemy’s main force.
2.Kriegsgechichtliche Einzelschriften* (1880); often quoted as, ‘No plan survives first contact with the enemy’
Or if you prefer a different version…
“Everybody has a plan until they get punched in the face"
Mike Tyson
This might suffice, although it has a much deeper meaning in the film:
“A compass, I learned when I was surveying, it’ll point you True North from where you’re standing. But it’s got no advice about the swamps and deserts and chasms that you’ll encounter along the way. If in pursuit of your destination, you plunge ahead heedless of obstacles and achieve nothing more than to sink in a swamp… what’s the use of knowing True North?”
— Lincoln (eponymous 2014 film)
Okay, True North may not be worth knowing, but North of North is!
I’ll be sure to Inuk into it.
This made me think of his nephew, who exclaimed to the Kaiser, “Your Majesty, we have lost the war,” soon after World War I started.