I did something last week that I had not done in decades – I tested a 9-volt battery by touching its posts to my tongue. Have you ever done that? My friends and I used to do it for kicks when we were kids. The unpleasant tingling sensation I felt told me that the battery was still good. Afterward, with a brain that may have just received a 9-volt kick start, I pondered that age-old question, “Why?”