At Harvard Business School's graduation ceremonies on Wednesday, May 27, the distinguished speaker was Scott Cook, the co-founder of Intuit, the $4.5-billion financial software company. Before Cook shared three of the lessons he's learned as an entrepreneur, two large screens flanking the stage continually flashed a single question: 

"What is one course lesson you will remember throughout your career?"

After the question flashed, the screens displayed handwritten answers from the HBS class of 2015. There were dozens of answers. Some were basic. Some were hackneyed. Some were profound. I wrote down as many as I could. Taken together, they paint a picture of the B-school takeaways that the HBS class of 2015 found to be most memorable. They also form a thorough and useful list of reminders that can help you keep perspective about what really matters in your life and career, going forward. 

1. Listen.

2. Every short-term decision has long-term implications.

3. Assume every email is a public document.

4. Don't run out of cash. 

5. It's not about who is right; it's about what is right. 

6. Think deeply about how you can empower those around you to be successful. 

7. Just be a decent human being. Oh, and listen more than you talk.

8. For a signal to really count, it must be costly.

9. Ask questions to learn different perspectives--inquiry vs. advocacy. 

10. Pursue your passions, not a paycheck. 

11. Even actions that are lawful can be awful. 

12. Government debt is not the same as corporate debt.

13. Let myself be vulnerable. 

14. Success at work can never compensate for failure at home. 

15. Don't worry alone; build a support team. 

16. Identify your sources of happiness and protect them. 

17. Kaizen (a.k.a. the practice of continuous improvement). 

18. The only sign of life is growth. 

19. Culture eats strategy for lunch; be safe, be sure.

20. The job is not as important as the rest of my life. 

21. It's never too late to turn back, change directions, or start anew.