What is meant by being vulnerable?

The following excerpt is from a samvaad (dialogue) session with Acharya Prashant.

Question: Sir, what is meant by being vulnerable?

Acharya Prashant (AP): The word ‘vulnerability’ is not a very likeable word. ‘Vulnerability’ to us is a consequence of the fact that there are forces outside of us that are hostile, aggressive and inimical because we need to protect and defend ourselves against these forces. We need to have armours, protection, defences made of thought.

We do not want to be vulnerable. We want to be defended. The moment somebody says, “Vulnerability is a virtue,” we feel being vulnerable means — exposing ourselves to attack. What we forget is the basics of duality. You are attacked only as long as there is something to be attacked. And when there is something to be attacked, you would always feel attacked, or threatened to be attacked.

It is not as if the universe is conspiring against you, it is just that the self that you have built up, lives on a diet of threats. It is not as if all the arrows and bullets are aiming at you, it is just that the armour that you have raised, is justified only by arrows and bullets.

It would look very stupid if we say, “I have thick armour,” when there is no threat of bullets. But because you must have armour, so what you see is only…