Two is One; One is None.

I am currently backing up all of the images from my memory cards.
It is an interesting learning experience.
I noticed I have taken so many photos. I try to back them up as best as I can.

I learned this saying from a friend:
"Two is One; One is None. Always have a backup"

You will be in a situation where you will run out of something you need the most.
There are times in my life when I ran out of film, batteries or even ink in a pen. I try to carry double or triple the quantity of the needed items when I am running errands or just out and about. Before the days of digital photography, I took a lot of photos with my film camera. I was at a graduation when the batteries died in my external flash. I wasn't able to get the shots I wanted. As a result, I was limited in what I can photograph. After that event, I started carrying extra batteries. This has saved me and other people when taking photos.

This is one of many lessons I always live by. Even if my pack gets heavy, I rather have the extra stuff than be empty-handed.