People who say it cannot be done should not interrupt those who are doing it.

Those who say it can't be done are usually interrupted by others doing it.

Those who say, 'It can't be done,' are usually interrupted by others doing it.

Never interrupt someone doing what you said couldn't be done.

People who attack others need rationalizations for doing so. We undermine those rationalizations.

It's useless to play lullabies for those who cannot sleep.