Let us analyse the statement, “The moon is out there in front of me whethere I look at it or not.”
The light from the moon reaches eyes, and the signal from the eyes goes to the brain and mind interprets the signal as moon. It is just the signal that is reaching the brain that the mind reads as moon. Even if the moon is not out there but the signal is there, mind still labels it as moon. In dream for example there is no moon out there but it still appears to be moon. So, actually what is interpreted depends solely on the signal. If moon is experienced, we cannot infer that physical moon is necessarily out there. Hence, the statement is not necessarily correct. Moon may appear to be out there, but what appears need not necessarily be real.
If we go a step ahead then where is the moon for the inert stone. It is only due to the body instruments (senses, brain etc.) does the moon exist for us. An ammeter shows the current, the brain shows the moon. There is no experience in the absence of a suitable measuring instrument or signal.
Since one can see the moon even by closing eyes, it is clear that it is mind that takes the shape of the moon. The logic that is applied to sight can be applied to sound, taste, smell, touch as well. Since it is mind that takes various forms, all we can say with certainty is that everything is mind only. Consciousness and still mind are synonemous. We Are THAT.
Mind-shield (Manomayakosha) is the barrier we form as children to protect ourselves from unpleasant feelings like hurt for example. This is because we believe that everything – including those feelings – is real. Once we realise that the reality is pure consciousness and what is not permanent is not real, this barrier of Manomayakosha must go making way for the bliss to shine. Manomayakosha acts as a barrier preventing bliss to shine which is our essential nature. It is okay to be somewhat vulnerable to feelings once it is known that the reality is non-dual. Even if self-realisation has not taken place, but just this understanding takes place that fears are behind many acts that we unconsciously do and it is those fears that prevent us from experiencing ever present bliss, we are ready to work towards diluting the shield of the mind (Manomayakosha) via self inquiry. Diluting Manomayakosha via self inquiry means finding the root cause of any feeling that arises which is of the nature of hurt, anxiety, approval seeking, low self-esteem etc.
PS: Fear is not the only component of Manomayakosha. Desire is also another major component. The above write-up concentrates on the fear aspect.