Duncan, have I not told you that when you think you know something, that is a most perfect barrier against learning?

Belief gets in the way of learning.

It is impossible to begin to learn that which one thinks one already knows.

The biggest obstacle to learning is assuming you already know.
Confidence is usually ignorance.

Nothing puts a greater obstacle in the way of the progress of knowledge than thinking that one knows what one does not yet know.

Fear, which is probably the biggest obstacle to any learning process, is a repressive force. It exists in the mind, and almost always it is based on something that might happen in the future, rather than what is happening now.

the greatest obstacles to the acquisition of knowledge — inasmuch as he possesses the consciousness that he does not know — and he has the moral courage to avow it.

There arises from a bad and inapt formation of words, a wonderful obstruction to the mind.

Fear is the greatest obstacle to learning. But fear is your best friend. Fear is like fire. If you learn to control it, you let it work for you. If you don’t learn to control it, it’ll destroy you and everything around you.

If we are caught by the obstacle of knowledge, even if truth comes knocking at our door, we will refuse to let it in.

You can't learn everything you need to know legally.

My schooling not only failed to teach me what it professed to be teaching, but prevented me from being educated to an extent which infuriates me when I think of all I might have learned at home by myself.

Nothing is a greater obstacle to our progress in knowledge, than a bad performance of a celebrated author; because, before we instruct we must begin with undeceiving.

He remarked that each of us was barred from silent knowledge by natural barriers, specific to each individual; and that the most impregnable of my barriers was the drive to disguise my complacency as independence.