Despite all the safeguards that your employer might put in place, what's one thing they can't control

The employer cannot hold the free will of the employees. They can have a sudden change of mind or a change of behavior that may affect a company even if it has already set a perfect management plan. 

I think the best asset of the company are the employees who work hard for the company's aim. It all relies on their dedication, loyalty, and innovation. I believe the company should always strive to keep them motivated.

What are the items? ?