Enlightenment is the natural state of our being. It sounds too simple. You may think of asking, why then only a fraction of the human population is enlightened. It is because, we give more importance to the mind and we always work on improving that. The pure awareness could be equated to a plain white paper. The mind is something like a painting on that white paper. When we work on the mind, we give a different coating over the existing coating, trying to create a better mind. The awareness is always pure and no external thing can pollute it. It is the emptiness itself. How could something stick to that emptiness.
The only way to get back to our real nature or being established in our pure awareness, is to make the mind pure. When the mind is perfectly pure, it becomes non-existent. For example, the pure water is perfectly transparent, tasteless and odourless. When there are some minerals or solute particles, it may become a solution and take a different name, by losing its purity. In the same way, the ultra pure mind is a non-existent mind.