Better Than Sliced Bread

With all the inventions out there how could anyone say what is the greatest? I love the cell phone, but compared to amazing medical devices that keep people alive or kitchen appliances that help keep food at safe temps it does not hold a flame or even sit on the same level of greatness. I guess this would all be based on personal preference. One might say the automobile is on the top of the list. Helping people get around and travel. Another person might argue the phone is higher on the list helping keep us in contact. My personal list includes the cell phone, washing machine and the incubators for newborns born to early.