The five Koshas work much like clouds when they cover the sun. The sun does not stop shining and is unaffected by the clouds and yet, when covered, its light appears much dimmer. When the clouds depart the sun is seen to be shining in all its glory still.
So it is with the essence of our being. It can be hidden from sight, but this does not mean that it has ceased to be.
Each kosha is progressively more refined and more subtle than the one before. Understanding their nature means being free of their limits. Being free of their limits makes it possible to know your self as you truly are.