As a premed student at Washington University in St. Louis, I had to take a difficult class in physics.  One day our professor was discussing a particularly complicated concept.  

A student rudely interrupted to ask "Why do we have to learn this stuff?"

"To save lives." the professor responded quickly and continued the lecture.

A few minutes later, the same student spoke up again.  "So how does physics save lives?" he persisted.

"It keeps the ignoramuses out of medical school," replied the professor.