To most people, a miracle is an event that appears unexplainable by the laws of nature or science, and therefore is supernatural or an act of God. A recent poll found that 61 percent of Americans believe in miracles. Do they exist? And to what extent? Should we believe? 48 Hours takes a close look at miracles of all shapes and sizes. Correspondent Bill Lagattuta travels to Rome to find out how the Vatican chooses a saint. Officials are in the process of deciding on the status of Katherine Drexel, a Philadelphia heiress who gave up her wealth to become a nun, and who, many believe, had healing powers. Correspondent Harold Dow reports on one desperate family who traveled to Lourdes in search of a miraculous cure to an incurable disease. Tanya Fisher had never met her birth mother. After searching for years, she finally found her, and discovered that they had actually been neighbors. Correspondent Susan Spencer reports from North Carolina.