Top professors are often asked to give talks on the hypothetical theme: what wisdom would they impart to the world if it were their last chance to do so? Watching healthy teachers consider their demise and ruminate over subjects dear to them can make for an intriguing hour. But a recent speech by Dr. Randy Pausch of Carnegie Mellon University was more than just an academic exercise. The 46-year-old father of three has pancreatic cancer and is not expected to live longer than a few more months. His last lecture was a rollicking and riveting journey through the lessons of his life.