So I can entertain that thought without accepting it.
Some educated minds can't do that. Some very uneducated people are very good at entertaining thoughts and not accepting them, either from wisdom or just from ignorance (like not accepting evolution because they don't like the idea of man and monkeys coming from a common ancestor, except most people get confused and think that it says that man came from monekys. But anyways, that's a tangent.)
I guess I accept what he probably meant, though - not just accepting something because you heard it.