Universal truths are unalterable facts. Mathematics is full of universal truths. The American Bill of Rights spells out exactly what the founding fathers found to be universally true. The fact that the only two things in life you have to do are pay taxes and die. Of course, since you don't have to work, you may not owe any taxes--yet.
For every action there is an opposite and equal reaction. I've seen this in action. As a kid, if I sat down to the dinner table and made disparaging remarks about the food on my plate, my mother would react by sending me to my room so I didn't have to consume said food.
What goes up must come down. Ask anyone on Wall Street about this truth. They may hem and haw, but after trying to confuse and influence you otherwise, those stock brokers will have to concede the truth.
All men are created equal. While that is a truth, don't believe that all women were created equal. But plastic surgeons are going to the bank daily, working to make every woman the same.
If you want the phone to ring, just go to the bathroom. I've tested this theory, and although many times I've found it to be true, I've discovered that sometimes you have to stay in the bathroom a mighty long time.