When engineers working on the very first iPod completed the prototype, they presented their work to Steve Jobs for his approval. Jobs played with the device, scrutinized it, weighed it in his hands, and promptly rejected it. It was too big. The engineers explained that they had to reinvent inventing to create the iPod, and that it was simply impossible to make it any smaller. Jobs was quiet for a moment. Finally he stood, walked over to an aquarium, and dropped the iPod in the tank. After it touched bottom, bubbles floated to the top. "Those are air bubbles," he snapped. "That means there's space in there. Make it smaller."