The following is apparantly a quote from the poetry of D.H. Rumsfeld, although I have not been able to get this confirmed 100% ....
Possibly from the Feb. 12, 2002, Department of Defense news briefing:

The Unknown
As we know,
There are known knowns.
There are things we know we know.
We also know
There are known unknowns.
That is to say
We know there are some things
We do not know.
But there are also unknown unknowns,
The ones we don't know
We don't know.

From the final issue of the The Whole Earth Catalog:


Stay Hungry. Stay Foolish.

From the late Steve Jobs:

People think focus means saying yes to the thing you've got to focus on.
But that's not what it means at all.
It means saying no to the hundred other good ideas that there are.

Loosely based on a statement the Dalai Lama:

When you talk,
you are only repeating what you already know;
but when you listen,
you might actually learn something new.

From the late Nelson Mandela:

I never loose,
I either win
or learn.

"Impossible is just a word thrown around by small men who find it easier to live in the world they've been given than to explore the power they have to change it. Impossible is not a fact. It's an opinion. Impossible is potential. Impossible is temporary. Impossible is nothing."

By the late Cassius Marcellus Clay, Jr. / Muhammad Ali.
Have not been able to trace back when he said this yet. Not sure if it was before or after 'The Greatest' changed his name. Either way the quote is inspiring.

Hope to run into more ...