If there was nothing wrong in the world there wouldn't be anything for us to do.
Success does not consist in never making mistakes but in never making the same one a second time.
The moment we want to believe something, we suddenly see all the arguments for it, and become blind to the arguments against it.
Progress is impossible without change, and those who cannot change their minds cannot change anything.
Some men see things as they are and ask why. Others dream of things that never were and ask why not.