"It is a bad plan that admits no modification."

You might recall a version of the quote from RTW:
"It is a bad plan that cannot be altered" - Publilius Syrus

It tells us, obviously, that a plan that cannot be altered is a bad plan. We need to realize when we need to change our plans and not be too rigid in our thinking.

Anyway, I'm working on an assignment for my Rhetorics course at the University and need to find another quote that says the same thing (basically) before tomorrow. So I thought I'd check with the wise people here at TWC.
Anyone know of any quotes like that?

Thanks
/Lesten

*Make your plans to fit the circumstances.
*A good plan today is better than a perfect plan tomorrow.

Not exactly what you're looking for but they're the only ones I know off the top of my head (from Patton)

"The best laid plans of mice and men oft go awry"

Those will do nicely.

Thanks.