What this quote is saying is that just because you have intelligence doesn't mean it's enough. For example, you can be a very smart person, but do you have a good character?. A lot of people can be smart but they can still do things that are wrong. A lot of people can use their mind in a completely wrong way. MLK believes we need a good character along side with intelligence. There should be people who uses their mind in the right way. People who has intelligence must also do good too.
