You cannot simultaneously prevent and prepare for war.

The surest way to prevent war is not to fear it.

The discovery of truth is prevented more effectively not by the false appearance things present and which mislead into error not directly by weakness of the reasoning powers but by preconceived opinion by prejudice.

Perhaps travel cannot prevent bigotry but by demonstrating that all peoples cry laugh eat worry and die it can introduce the idea that if we try and understand each other we may even become friends.

As time goes on we get closer to that American Dream of there being a pie cut up and shared. Usually greed and selfishness prevent that and there is always one bad apple in every barrel.

There may be times when we are powerless to prevent injustice but there must never be a time when we fail to protest.

Time is what prevents everything from happening at once.

If we as a nation are to break the cycle of poverty crime and the growing underclass of young people ill equipped to be productive citizens we need to not only implement effective programs to prevent teen pregnancy but we must also help those who have already given birth so that they become effective nurturing bonding parents.

For a long time many believed that there would be an automatic adjustment and counted on a rapid increase in the wages of the emerging nations on our advances in technology and the costs of transport preventing disruption. But this reassuring analysis is out of date.

I have argued above that we cannot prevent the Singularity that its coming is an inevitable consequence of the humans' natural competitiveness and the possibilities inherent in technology.