Non-duality that does not include duality is not non-dual.

What is it to gaze out upon the invisible with emptiness in your eyes? 

If there is fear, relax into the fear. If there is anxiety, relax into anxiety. If there is joy, relax into joy. If there is peace, relax into peace.

If you experience doubt, difficulty or aversion in meditation then rest into the state of doubt, difficulty or aversion. There is no way around this great awareness.

Become absorbed into the vast nature of presence and then remain. Remain without aim. Remain without question. Allow concentration to settle into itself and become aware of its action as effortless.