If the slightest probability for an unpleasant event to happen exists, the event will take place, preferably during a demonstration.
If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.
If there isn't a law, there will be.
If there is a 50-50 chance that something can go wrong, then 9 times out of 10 it will.
If there is light at the end of the tunnel...order more tunnel.
If things were left to chance, they would be better.
If two wrongs don't make a right, try three.
If we learn by our mistakes, some of us are getting one great education!
If you aim for the stars but only make it to the moon, remember there are people who have not yet made it to the moon.
If you are already in a hole, there is no use to continue digging.