"What's the foundation of the modern economic system?" Professor Collins asked his class. He looked around and noticed that most of his students weren't paying attention. "No one? What about you, Kate?"

"Umm," Kate was thoughtful for a moment and then said, "The relationship between the real economy and human resources?"

"Are you asking me or telling me?" He smiled and said, "You're partially right, but that's just one aspect of it. There are three pairs of relationships that we can consider as the foundation of the modern economic system." He saw one of his students yawned, and two at the back of the classroom were passing notes. Kate was now looking at her mobile phone. Most of them were looking at the wall clock waiting for the bell to ring. He stood there quietly, and no one seemed to be aware that their teacher had stopped his lecture.

Steven, who was sitting next to Kate, raised his hand, "Can three sets of relationships explain something that complex?"

"A good question, Steven," the Professor said, smiling. "Let's see what these relationships are and how they work." As long as one student was paying attention, he'd keep doing his job well.