Someone played a recording of Luang Pu's teaching on the "atom of the mind" and asked the teacher to expand on what it means and how it relates to meditation and physical and mental wellbeing.

What the atom of the mind is

Everything — objects, people, everything in the atmosphere — is made of atoms far smaller than cells. Scientists have probed deeper still, down through protons, neutrons, and electrons, and further yet, until what remains is simply emptiness — yet within that emptiness are waves with their own distinctive patterns, which are the very origin of all things. In science this is called string theory, or the "theory of everything," and it's enough to bridge Buddhist science and physical science: what scientists have discovered is, in essence, the three natures — the wave-pattern of the wholesome, the wave-pattern of the unwholesome, and the wave-pattern of the neutral-drifting — the root cause behind the arising of all beings and all things.

With regular meditation, the mind grows clearer, and the elements within us — earth, water, wind, fire, space, and consciousness — grow purer along with it. The atomic structure within us, ordinarily riddled with gaps like a hollow lattice, gradually becomes denser and more orderly, until its purity appears as a small, clear sphere — what's called a "diamond-bright heart." Once the mind's atoms are arranged in dense, orderly formation, the current of defilement can no longer slip in.

How defilement slips into the gaps between atoms

Defilement is the unwholesome current that pulls the mind away from its inner base and out toward attachment to external things, making the mind coarse. Once coarse, the gaps between the particles of our atomic structure become vulnerable, letting defilement slip in — producing ignorance, suffering, and being driven to create karma with its consequences. When the unwholesome takes hold of the mind, it manipulates our thoughts and feelings, convincing us that unwholesome thoughts are our own. Once we accept them as ours, we become bound within its domain: consciousness is drawn outward through the eyes, ears, nose, tongue, body, and mind to perceive sights, sounds, smells, tastes, and touches with a specific purpose — to draw in unwholesome energy to power the unwholesome system. These defilements lodge in the center of the space and consciousness elements within the sphere of Dhamma, throwing the earth, water, wind, and fire elements out of balance — and the body responds with a sense of tightness, heaviness, sudden heat, or even trembling, depending on how intense the emotion is.

What to do when feeling agitated or tight

When heat or tightness or distress arises in the body, repeat inwardly, "still within stillness, calm within calm," over and over. The electrons that have been spinning at high speed, colliding and generating heat, gradually slow down; the "haze" from that friction gradually thins; and the heat or trembling gradually subsides. Wherever we focus within the body, that spot brightens and is purified first, and the brightness then spreads outward. If at some point everything feels empty and blank, with nothing visible at all, there's no need for discouragement — subtle impurities still remain. Keep holding the mind still, continuing with whatever meditation method has worked before, until the mind reveals its own clarity; brightness then appears, develops into a luminous sphere, and gradually grows clearer still.

The process of gradual liberation

When the earth, water, wind, fire, space, and consciousness elements merge into one within the sphere of Dhamma, the mind is drawn inward and settles at the center. From there, it becomes a matter of the wholesome system's own automatic process, passing the mind onward, stage by stage — from the sphere of Dhamma to the sphere of precepts, to concentration, to wisdom, to liberation, and to the vision of liberation. Each sphere serves as a refining instrument, purifying the mind further; all that's needed is to remain still within. This process carries onward — from the refined human body to the celestial body, the refined celestial body, the Brahma body, the refined Brahma body, the formless Brahma body, the refined formless Brahma body, and further, to the Dhamma body. Those without enough accumulated energy or grounding in the practice tend to linger longest at the formless Brahma body stage, but with sufficient virtue and meditative depth, liberation comes more readily at each stage. All of this is the ongoing process of rebalancing the three natures — reducing the strength of the unwholesome and the neutral-drifting, and steadily increasing the share of the wholesome.