A man, complaining of headaches, entered a hospital for diagnostic tests. A doctor examined the results for a brain scan and told the patient, "I have bad news and good news for you. The bad news is that you have a serious brain disease and will die without treatment. The good news is that this hospital has developed a new procedure for brain transplants and due to a car accident this morning two 'fresh' brains are available: one is from a taxi driver and the other is from a scientist. The brain of the taxi driver costs $225,000, while that of the scientist is only $29.95." Puzzled, the patient asked, "Why is the scientist's brain was so much cheaper?" The doctor replied, "It's used..."