Opinion is usually something which people have when they lack comprehensive information.

Sometimes a pessimist is only an optimist with extra information.

Talent is the presence of ability and absence of understanding about the source and operation of knowledge.

Knowledge is something which you can use.
Belief is something which uses you.

Two people can illustrate crudity to you.
The first is the crude man, whom you see perceiving the diamond as a stone.
The other is the refined man, who makes clear to you the crudity of the first one.

Because there is a word for perfection, people will always imagine that they know it.