When the Buddha taught that clinging is the source of suffering, he used a list of five aspects of experience as shorthand for all the things we cling to. This list, called the “five aggregates” (khandha), is part of the definition of suffering in the famous first discourse, known as “Setting in Motion the Wheel of the Dhamma” (SN 56.11).

Now this, bhikkhus, is the noble truth of suffering: birth is suffering, aging is suffering, illness is suffering, death is suffering; union with what is displeasing is suffering; separation from what is pleasing is suffering; not to get what one wants is suffering; in brief, the five aggregates subject to clinging are suffering. (Setting in Motion the Wheel of the Dhamma, SN 56.11)

The list of the five aggregates appears in many important teachings in addition to the Buddha’s first discourse, such as in the Foundations of Mindfulness (Satipaṭṭhāna Sutta, MN 10), where it is part of the fourth foundation. It is the backbone of important discourses in the Majjhima Nikāya (The Middle-Length Discourses) such as MN 28, 44, 109, and 131, and the subject of 159 different discourses in one of the longest chapters in the Connected Discourses, or Saṁyutta Nikāya (SN 22). Along with the list of the six sense bases, the five aggregates is one of the primary ways the Buddha analyzed experience.

The 5 aggregates are:

1. Form (rūpa)
2. Feeling (vedanā)
3. Perception (saññā)
4. Mental Formations (saṅkhārā)
5. Consciousness (viññāṇa)

Form (rūpa)

The first aggregate, form, encompasses everything in the physical world, particularly oriented toward objects and bodies that we see, but including material form as perceived through any of the senses.

Feeling (vedanā)

Feeling refers to “feeling tone,” how everything is perceived as either pleasant, unpleasant, or neutral. This is the same important aspect of our experience that is the subject of the second foundation of mindfulness.

Perception (saññā)

Perception is the sensing and recognition process by which sensory information is received and processed.

Mental Formations (saṅkhārā)

Mental formations refers to the narratives, emotions, concepts, and choices that are such a large part of how we understand and interact with the world. Choice is central to this aggregate, which is sometimes called “volitional formations,” emphasizing the power our choices have to determine our emotional states and experiences. Because saṅkhārā emphasizes choices, and the actions that flow from them, it is an important part of the teaching on kamma (Sanskrit: karma) and ethics, and is the second link in the process of Dependent Origination after ignorance.

Consciousness (viññāṇa)

Consciousness is the simple quality of being aware of sensory experiences as they happen. Importantly, viññāṇa does not refer to consciousness as a kind of subtle self or true nature. Consciousness is always consciousness of something—never separate from sense experience. Because of this, like all the other aggregates, consciousness cannot be described as “I or mine,” and is therefore “not-self” or anattā.

Together, the set of the aggregates is one way of describing everything we can know and experience. And since we can cling to anything, both pleasant and unpleasant, the list becomes a useful way of exploring how clinging and attachment cause suffering.

The Aggregates: Fuel for the Fire of Attachment

The Pāli word khandha literally means “heap” or “group,” and refers to a set of things. One evocative meaning that may have been part of how the Buddha’s community understood the word is “like a bundle of wood to be used for fires”—in other words, fuel. Scholar Richard Gombrich and monastic Ṭhānissaro Bhikkhu have explored the extended use of fire as a metaphor in the Buddha’s teaching, and the aggregates are central to this imagery. The metaphor touches on how pre-Buddhist Vedic culture related to the element of fire, but a simple version of the teaching emphasizes that our clinging to things, which is the cause of suffering, is like fire clinging to wood as it burns.

If the khandha are fuel in the metaphor, what is the fire? The fire is grasping, aversion, and delusion, which the Buddha describes in the famous “Fire Sermon” (SN 35.28). The word we translate as “clinging” is upādāna, which literally means “feeding,” with the same meaning as when we say in English that we “feed a fire.” The end of suffering is then like putting out a fire by denying it further fuel. Sure enough, the word for enlightenment, nibbāṇa, literally means “extinguishment,” as in how a fire goes out.

The fire metaphor offers a visceral teaching on how attachment to various kinds of experiences causes our suffering and dissatisfaction. The list of the aggregates as types of fuel breaks down experience into five important aspects, so we can clearly see how subtle and pervasive attachment really is. We get attached to forms—our own bodies, other bodies, and all kinds of objects and images. We get attached to feelings, to perceptions, and to all the stories and emotions that spin around them. And we even get attached to consciousness itself, which comes out poignantly as fear of death and loss.

In the daily chanting in the Theravāda monastic traditions, the aggregates are described in relation to the three characteristics shared by all conditioned things: impermanence, suffering/unsatisfactoriness, and not-self. Realizing with insight that the aggregates are imperfect, impermanent, and impersonal helps us let go of the stories and habits by which we cling to them.

Form is impermanent
Feeling is impermanent
Perception is impermanent
Mental formations are impermanent
Sense-consciousness is impermanent

Form is not-self
Feeling is not-self
Perception is not-self
Mental formations are not-self
Sense-consciousness is not-self

All conditions are transient
There is no self in the created or the uncreated

— Morning Pūjā, Forest Saṅgha

One of the most important ways the aggregates are used in practice is as objects for mindfulness. The instruction in the Satipaṭṭhāna Sutta, where they appear in the fourth foundation of mindfulness, is to bring mindfulness to the arising and passing of each aggregate. This means that we stay present with our senses (“form”), noticing change as we move through our day, and feel how emotions and thoughts (“feelings, perceptions, mental formations”) appear and pass away as conditions shift. We can even become aware of how sensory awareness (“consciousness”) changes as our attention moves between things. This is how the insight into impermanence develops and deepens.