Came across the following quotes while reading a book on Agile estimation:

“Planning is everything. Plans are nothing.”
–Field Marshal Helmuth Graf von Moltke

“No plan survives contact with the enemy.”
–Field Marshal Helmuth Graf von Moltke

“A good plan violently executed now is better than a perfect plan executed next week.”
–General George S. Patton

“To achieve great things, two things are needed: a plan, and not quite enough time.”
–Leonard Bernstein

“Prediction is very difficult, especially about the future.”
–Niels Bohr, Danish physicist

“There’s no sense in being precise when you don’t even know what you’re talking about.”
–John von Neumann