Today one of my students (a business major) e-mailed to ask me some technical question about accounting or marketing or some such thing. I had to reveal to him that I didn't know the answer because I had never in my life studied these subjects. I went on to explain:

Business students need to study economics in the same way that engineering students need to study physics. This is because economics (physics) is the theoretical underpinning for business (engineering). But the reverse is not true. Economics students don’t need to study business any more than physics students need to study engineering. Economists (physicists) don’t need to know how to run businesses (build buildings) to understand the theory of an economy.

At least that's my story and I'm sticking with it.