The Sense Bases and Elements (Chapter 15)

What this chapter covers: This chapter explains two ways of mapping all experience: the twelve sense bases (ayatana) and the eighteen elements (dhatu). These are not new realities beyond what was covered in the aggregates — they are the same mental and material phenomena reclassified to reveal how consciousness arises at each sense door. Understanding them dissolves the illusion of a unified “self” behind experience.

Part A: The Twelve Sense Bases

The twelve sense bases (ayatana) are:

Eye base and visible-form base
Ear base and sound base
Nose base and odour base
Tongue base and flavour base
Body base and tangible-object base
Mind base and mental-object base

What “Base” Means

The word “base” carries several related meanings. A base is a place of activity — a home ground where consciousness operates. Think of it in five ways:

A dwelling place — consciousness lives in the eye, ear, and so on, because it depends on them to exist
A resource — like a mine of gold or silver, the bases are the raw material consciousness draws on
A meeting place — consciousness and its companions gather at a base, using it as physical support, door, and object
A birthplace — consciousness arises right there, at whichever base serves as its support and object
A cause — when the base is absent, the corresponding consciousness is absent too

In the broadest sense, the bases are called “bases” for three reasons. They activate consciousness — each base triggers its own type of knowing. They provide range for what arises — they give consciousness room to operate. And as long as the cycle of rebirth has not ended, they keep leading experience onward.

How Many and Why Twelve

The eye and the other sense organs are also types of mental objects. So why list twelve bases instead of simply saying “mental-object base”? Because the classification exists to define the specific door-and-object pair for each of the six types of consciousness.

Only the eye base is the door, and only visible forms are the object, for the group of consciousness containing eye-consciousness. The same applies for each of the other senses.

For the sixth type — mind-door consciousness — the door is one part of the mind base (the life-continuum mind), and the object is whatever falls under the mental-object base that is not shared by the other five.

The Order of Teaching

The eye is taught first because its domain — visible form — is the most obvious. Next come the ear, nose, tongue, and body. The mind base comes last because it ranges over the domains of all five senses. Each external base is taught right after its corresponding internal base — visible forms after the eye, sounds after the ear, and so on.

There is another way to understand this order. It follows the formula: “Due to eye and visible forms, eye-consciousness arises. Due to mind and mental objects, mind-consciousness arises.”

In Brief and in Detail

In brief, the twelve bases are simply mind and matter. The mind base and one portion of the mental-object base count as mind. Everything else counts as matter.

In detail:

The eye base is, by kind, simply eye sensitivity. But classified by conditions, destiny, species, and person, it is endlessly varied. The same goes for the ear, nose, tongue, and body bases.
The mind base, classified by wholesome, unwholesome, resultant, and functional consciousness, is eighty-nine kinds — or one hundred and twenty-one kinds. Classified by physical basis and progress, it is infinitely varied.
The visible-form, sound, odour, and flavour bases are infinitely varied when classified by differences and conditions.
The tangible-object base is three kinds: earth element, fire element, and air element. Classified further, it is many kinds.
The mental-object base is many kinds: feeling, perception, mental formations, subtle matter, and the unconditioned (nibbana).

How to Regard the Bases

All conditioned bases should be seen as having no origin and no destination. Before they arise, they have no individual nature. After they pass away, their nature is completely dissolved. They exist only in dependence on conditions, between the past and the future. No one has control over them.

The bases should also be seen as incurious and uninterested. The eye and visible forms don’t think, “Let consciousness arise from our meeting.” They have no intention to produce consciousness. It is simply an absolute rule that eye-consciousness comes into being when eye meets visible form. The same goes for the others.

Furthermore, the internal bases should be regarded as an empty village — devoid of permanence, pleasure, and self. The external bases should be regarded as village-raiding bandits, because they assault the internal ones. As the Buddha said: “The eye is harassed by agreeable and disagreeable visible forms.”

The internal bases are like six creatures tied together, each pulling toward its own territory. The external bases are like the places those creatures want to go.

Part B: The Eighteen Elements

The eighteen elements (dhatu) are:

Eye element, visible-form element, eye-consciousness element
Ear element, sound element, ear-consciousness element
Nose element, odour element, nose-consciousness element
Tongue element, flavour element, tongue-consciousness element
Body element, tangible-object element, body-consciousness element
Mind element, mental-object element, mind-consciousness element

What “Element” Means

The word “element” means a basic constituent — a “sort” of reality. Just as in the world we speak of different ores (elements of gold, silver, and so on), these are the basic constituents of experience. Just as the body can be analysed into its constituent juices, blood, and so on, so the entire personality — the five aggregates — can be analysed into these eighteen constituents, each distinguished by its own characteristic.

The mundane elements sort out the many kinds of suffering in the cycle of rebirth. They are borne by living beings like a burden by burden-carriers. They are mere sortings-out of suffering, because no one has mastery over them.

Most importantly, “element” is a term for what is soulless. To abolish the perception of a soul, the Buddha taught the elements in passages like: “This person has six elements.”

Why Eighteen

In the discourses and the Abhidhamma, many other elements are mentioned — illumination, beauty, the four formless-sphere elements, sense-desire, renunciation, ill-will, non-ill-will, cruelty, non-cruelty, pleasure, pain, joy, grief, equanimity, ignorance, earth, water, fire, air, space, consciousness, the formed, the unformed, and more. Why classify by these eighteen rather than all of them?

Because, as far as individual nature is concerned, every existing element is already included in the eighteen.

The illumination element is just the visible-form element.
The beauty element is bound up with visible form and so on.
The formless-sphere elements: their consciousness is mind-consciousness element; the rest is mental-object element.
Sense-desire element is either just the mental-object element, or all eighteen elements, depending on context.
Renunciation, ill-will, cruelty, non-ill-will, non-cruelty, pleasure, pain, joy, grief, equanimity, ignorance, initiative, launching, and persistence — all fall under the mental-object element.
Inferior, medium, and superior elements are the eighteen elements themselves, classified by quality.
Earth, fire, and air elements are the tangible-object element. Water and space elements are mental-object element only.
“Consciousness element” summarizes the seven consciousness elements.
Seventeen elements plus part of the mental-object element are the formed element. The unformed element is one part of the mental-object element only.

So every element that exists is covered by the eighteen.

Furthermore, the eighteen are taught to eliminate the perception of a soul in consciousness. Some beings see a permanent self in the knowing nature of consciousness. The Buddha made evident not only that consciousness is multiple — eye-, ear-, nose-, tongue-, body-consciousness, mind, and mind-consciousness — but also that it is impermanent, since it depends on eye-and-visible-form and so on as its conditions.

By methods brief and long as need may be, He taught the Dhamma, so that from beings’ hearts, If they have wit to learn, the dark departs, Melting in the Good Dhamma’s brilliancy.

The Order of Teaching

The order follows the pattern of cause and result. The pair — eye element and visible-form element — are the cause; eye-consciousness element is the result. So for each triad.

How the Elements Are Reckoned

The eye element is one thing: eye sensitivity. Likewise for the ear, nose, tongue, body, visible-form, sound, odour, and flavour elements.
The tangible-object element is three things: earth, fire, and air.
The eye-consciousness element is two things: wholesome and unwholesome kamma-result. Likewise for ear-, nose-, tongue-, and body-consciousness.
The mind element is three things: five-door adverting, and wholesome and unwholesome resultant receiving.
The mental-object element is twenty things: three immaterial aggregates, sixteen kinds of subtle matter, and the unconditioned.
The mind-consciousness element is seventy-six things: the remaining wholesome, unwholesome, and indeterminate consciousnesses.

Conditions

The eye element is a condition for eye-consciousness in six ways: dissociation, pre-nascence, presence, non-disappearance, support, and faculty. The visible-form element is a condition for eye-consciousness in four ways: pre-nascence, presence, non-disappearance, and object. The same pattern holds for ear and sound, and so on.

Not only are the eye and visible forms conditions for eye-consciousness, but also light and attention. The ancient teachers summarised it this way:

Eye-consciousness arises due to eye, visible form, light, and attention
Ear-consciousness arises due to ear, sound, an opening, and attention
Nose-consciousness arises due to nose, odour, air, and attention
Tongue-consciousness arises due to tongue, flavour, moisture, and attention
Body-consciousness arises due to body, tangible object, earth, and attention
Mind-consciousness arises due to life-continuum mind, mental object, and attention

How to Regard the Elements

All conditioned elements should be regarded as cut off from past and future, void of permanence, beauty, pleasure, or self, and existing only in dependence on conditions.

As for individual elements, consider these images:

The eye element is like a drum skin, visible form is like the drumstick, and eye-consciousness is like the sound. Or: the eye is like a mirror, visible form is like the face, and eye-consciousness is like the reflection. Or: the eye is like sugarcane, visible form is like the mill, and eye-consciousness is like the juice. Or: the eye is like the lower fire-stick, visible form is like the upper fire-stick, and eye-consciousness is like the fire. The same pattern applies for each sense.
The mind element is the forerunner and follower of the five sense-consciousnesses as they arise.
In the mental-object element: feeling should be regarded as a dart and a stake. Perception and formations are like a disease, connected to that dart and stake. An ordinary person’s perception is like an empty fist — it produces pain through disappointed desire. Or like a forest deer spooked by a scarecrow — it grasps the sign incorrectly. Formations are like men who throw you into a pit of hot coals — they throw you into rebirth. Or like thieves chased by the king’s men — they are pursued by the pains of birth. Or like seeds of a poison tree — they are the root cause of the continuity of the aggregates. Matter should be regarded as a razor-wheel, the sign of many dangers. But the unconditioned element should be regarded as deathless, as peace, as safety — because it is the opposite of all suffering.
The mind-consciousness element is like a forest monkey that never stays still on its object. Or a wild horse, difficult to tame. Or a stick flung into the air, falling any which way. Or a stage dancer, adopting the guise of various defilements like greed and hatred.

This is the fifteenth chapter, “The Description of the Bases and Elements,” in the section on the Development of Understanding in the Path of Purification, composed for the purpose of gladdening good people.