The case for past lives BY DAVE BARRY (This classic Dave Barry column was originally published on Jan. 19, 1997.) To be honest, I had completely forgotten that in a former life I was Mozart. You know how certain things tend to slip your mind, like where you left your car keys, or the fact that you used to be a brilliant Austrian composer who died in 1791? Well, that's exactly what happened to me. I was reminded of my former life recently when I received a book called ''Spirit at Work,'' by Lois Grant, who has had a number...