"Empty, luminous, and infinite in potential, mind can be understood as having five basic qualities: emptiness, mobility, clarity, continuity, and stability. Each of these corresponds respectively to the five principal elements of space, air, fire, water, and earth.

We have already described mind as not being a tangible thing: it is indeterminate, omnipresent, and immaterial; it is emptiness, with the nature of space.

Thoughts and mental states constantly arise in the mind; this movement and fluctuation is the air element’s nature.

Furthermore, mind is clear; it can know, and that clear lucidity is the fire element’s nature.

And mind is continuous; its experiences are an uninterrupted flow of thoughts and perceptions. This continuity is the water element’s nature.

Finally, mind is the ground, or basis, from which arise all knowable things in samsara as well as nirvana, and this quality is the earth element’s nature."

From: "Luminous Mind: The Way of the Buddha"

~ Kyabje Kalu Rinpoche