"So begins the genetic revolution. Without PCR, genetics is like trying to do experiments on one droplet of milk sitting on a white plate. The milk is hard to find, and you only have enough of it to try one thing - such as add a droplet of orange juice and see what happens - and that's it. You are limited in experimenting if you only have a tiny amount to play with. PCR makes genes by the milk pail, and scientists are thrilled."

The article is nice clear discussion
of PCR and its inventor.