One-Tenth

I expect that the ability of a person shown in public is only one-tenth of his/her whole ability.
This is like an iceberg floating on the ocean.
It's often said that an iceberg we can see above the ocean is actually only one-tenth of the whole.
In other words, we can only show one-tenth of our whole ability to the public. So, if you think someone is stupid, then you must need to look the person more deeply, because he must have the ability that is far bigger than just the first look.
So, be careful when you judge people.