Mind, on the ordinary level, is obscured by concepts, different states of thinking and preconceptions, and so on. In order to recognise the essential nature of the mind, therefore, we have to peel off these different layers and clear away these obscurations. Then we shall see the true face of our own minds.
If you undertake such practices, such experiments, when you say ‘consciousness’, it will not be a mere word. You will be able to understand what it is. Consciousness is a phenomenon that is nonobstructive; it is nonphysical and has the quality of luminosity. It is analogous to a crystal. If a crystal is placed on a coloured surface, the real clarity of that crystal will not be seen. If it is removed from anything coloured, however, then its real form will be seen.
The luminosity of the mind, the nature of clarity of the mind, is something that I cannot simply explain in words to you. But if you undertake this kind of experiment on your own, you will begin to understand,’ Ah, that’s the luminosity of the mind!’
From Dalai Lama’s Teachings