So, this is a picture of my bedroom door. Can you see the big hole and the smaller dent beside it? Those craters were created when my right shoulder and head collided against the door. 
This happened one morning when my caregiver and I had both lost our balance, but since it didn't hurt much at the time, I simply laid myself down with an ice pack. I even went to sleep that night without any painkillers, but the next morning when I went to the clinic, the doctor took an X-ray and said, "You've dislocated your arm. It's broken, too" ...

This got me thinking about the words Anshin (Sense of security) and Anzen (safety).  By the way, "Anshin" is a word that does not translate accurately into English. 
There is no way that Anshin and Anzen can co-exist. Having  a sense of security does not mean you are 100% safe. Being safe does not mean you can rest assured 100%. 
Always keep in mind that accidents do occur.