'" Al-Ahnaf ibn Qays said:
Khaleel ibn Ahmad said:

"The people are of four
types:

1. A man who knows, and
knows that he knows. This
is the scholar, so take
from him.

2. A man who knows, but
doesn't know that he
knows. This one has
forgotten, so remind him.

3. A man who doesn't
know, and knows that he
doesn't know. This one is
a student, so teach him.

4.A man who doesn't
know, and doesn't know
that he doesn't know.
This one is an idiot, so
reject him."

Number 3.