If something is capable of being X, then it tends to be a little X

If people are capable of being evil, then they tend to be a little evil. If we're capable of greatness, then each of us tends to be a little great

If something is capable of full greatness, then (in general) it tends to be great just a little. A few individuals will be fully great. A few will be zero great. Most will be a little great—will have moments or elements of greatness

The chance of a person being fully great is very small. The chance of a person having no greatness is also very small. So most of us are a little bit great

I think that's great!