Those who don't know the ...

Those who don\'t know the mistakes of the past won\'t be able to enjoy it when they make them again in the future.
Those who don't know the mistakes of the past won't be able to enjoy it when they make them again in the future.
 Diane Duane

More phrases

If one does not know to which port one is sailing, no wind is favorable.
What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.
We are masters of the unsaid words, but slaves of those we let slip out.
I have always found that mercy bears richer fruits than strict justice.
A lie gets halfway around the world before the truth has a chance to get its pants on.

Quotes from the same author

But even in your world it’s a byword. Men will fight bravely and be heroes, but for last-ditch defense against any odds… get a Mother.
 Diane Duane
The city breathing, burning, living the life thy had preserved. Ten million lives and more. If something should happen to all that life - how terrible! Nita gulped for control as she remembered Fred's word of just this morning, an eternity ago. And this was what being a wizard was about. Keeping terrible things from happening, even when it hurts. Not just power, or control of what ordinary people couldn't control, or delight in being able to make strange things happen. Those were the side effects - not the reason, the purpose.
 Diane Duane
Power," Nita heard her father say behind her. "Creation. Forces from before time. This is--this business is for saints, not children!" "Even saints have to start somewhere," Carl said softly. "And it's always been the children who have saved the universe from the previous generation and remade the universe in their own image.
 Diane Duane
It's always been the children who have saved the universe from the previous generation and remade the universe in their own image.
 Diane Duane