"The most expensive part of a building is the mistakes." ~ Ken Follett in The Pillars of the Earth
This is true. The biggest price that we pay in life is for our mistakes. The life of every human being is driven mostly by his mistakes and to a small extent by his correct ideas—that is why history reads like a compendium of manmade disasters. All men constantly face the danger of being wrong, of being very wrong, of being hopelessly wrong.