What is the meaning of "still waters run deep"?

The meaning of "still waters run deep" is:

a quiet person may be extremely wise and intelligent


What is the definition of "still waters run deep"?

The definition of "still waters run deep" is:

a quiet person may be extremely wise and intelligent



"still waters run deep" means

a quiet person may be extremely wise and intelligent

Example Sentence:

That guy in our class is always very shy and quiet, so I decided to talk to him on the bus yesterday. He was so funny and smart, we had a great conversation. Still waters run deep, I guess!

still waters run deep