“People were constantly asking for my advice: ‘Tell me what five albums I should buy now,’ or ‘Tell me what are the five best heavy metal albums of all time,’ ” Mr. Scaruffi said. “Eventually you get tired of answering the same question, and you prepare a list. Then the list becomes many lists.”

“Probably my biggest ambition would be to write a history of knowledge,” he said. “Something that packages all of my interests together: literature, science, philosophy, politics — whatever.”