Each moment of our experience is made up of a multitude of variables. The five aggregate factors of experience (phung-po, Skt. skandha, aggregates) constitute a classification scheme for those variables – in other words, for the nonstatic (impermanent) components.
The word aggregate means a collection, thus each aggregate is a collection of many components. The components of one aggregate may be different types of phenomena, such as love and anger, or they may be different possibilities of one phenomenon, such as the feeling of different levels of happiness. When part of experience, each variable component changes from moment to moment and has a different length of continuity.
Since the definition of what exists is what is validly knowable and since everything validly knowable can be an object of our experience, everything that exists can be an object of our experience. This means that all nonstatic phenomena can be classified among the five aggregates. Some are connected with our mental continuums (sems-rgyud, mind-stream), such as our own happiness; and some are connected with the mental continuums of other sentient beings, such as the happiness of someone else. Others are not connected with any mental continuum, such as a rock. Static phenomena, such as space, may be part of our experience, but they are not included in the classification scheme of the five aggregate factors.
The five aggregate factors, then, resemble five bags. Each moment of our experience has one or more components from each of the bags, and every variable that constitutes our experience is in one or another of the bags. The bags, however, are merely abstractions imputed on the basis of collections of components. The bags and their components do not exist on their own somewhere, either inside or outside of us. When an aggregate factor, such as happiness or anger, is not part of our experience of the moment, it does not exist as something findable somewhere else.
The Aggregate of Forms of Physical Phenomena
Each moment of our experience has one or more forms of physical phenomena as part of it. They fall within the eleven groupings of the aggregate of forms of physical phenomena (gzugs-kyi phung-po, aggregate of forms).
The five sensory objects:
- Physical sensations.
The five physical cognitive sensors (dbang-po, sense-power):
- Photosensitive cells of the eyes
- Sound-sensitive cells of the ears
- Smell-sensitive cells of the nose
- Taste-sensitive cells of the tongue
- Physical-sensation-sensitive cells of the body.
The eleventh category is all forms of physical phenomena cognizable only by mental cognition. Technically, they are:
- Forms of physical phenomena included only among the cognitive stimulators that are (all) phenomena (chos-kyi skye-mched-kyi gzugs). They include forms of physical phenomena that are imperceptible to our physical cognitive sensors, such as the images and sounds we experience in dreams. The previous ten components of this aggregate comprise the five external and the five internal cognitive stimulators, for example the cognitive stimulators that are sights (gzugs-kyi skye-mched), the cognitive stimulators that are (the photosensitve cells of) the eyes (mig-gi skye-mched), and so on.
In a loose sense, even when we are in deep sleep without dreaming, we still have a body as the basis for our experience of sleep. Thus, each moment of our sleep has an aggregate of forms of physical phenomena.
The Aggregate of Feelings of a Level of Happiness
The English word feelings spans a large variety of meanings. It includes feeling levels of happiness or unhappiness; feeling tactile sensations, such as smooth or rough; and feeling physical sensations, such as hot or cold, pleasure or pain, or motion. Feelings can also refer to emotions, such as feeling angry, or intuitions, such as feeling it will rain tomorrow. It can also mean aesthetic sensitivity, such as artistic feeling, or emotional sensitivity, such as hurt feelings.
The aggregate of feelings of a level of happiness (tshor-ba'i phung-po, aggregate of feelings) includes only the first type of feelings in this list. Each moment of our experience, whether it be with sensory or mental cognition, has as one of its components a feeling of some level of happiness on the spectrum from total happiness to neutral to total unhappiness or suffering.
The Aggregate of Distinguishing
Each moment of our experience also includes a factor from the aggregate of distinguishing ('du-shes-kyi phung-po, aggregate of recognition). Distinguishing is a mental factor (sems-byung, subsidiary awareness ) that is part of the sensory or mental cognition of anything. It distinguishes the special characteristic feature of an object of focus from the special characteristic features of what is not the object of focus. For example, in seeing someone's face, it distinguishes the shape and color of the face from the shapes and colors of everything that is not the face – in other words, from everything else seen at the moment in the cognitive-field of vision.
Thus, recognition is not an accurate translation of this type of mental factor. Recognition implies having previously experienced something similar to what we are experiencing now, comparing the two objects of experience, and cognizing them together as belonging to the same category. Thus, although the process of recognition includes distinguishing, it also entails deep awareness of equalities (mnyam-nyid-kyi ye-shes), which is not a component of this aggregate factor.
The Aggregate of Other Affecting Variables
The aggregate of other affecting variables ('du-byed-kyi phung-po, aggregate of volitions, aggregate of karmic formations) comprises all variables, affecting the experience, that are not included in the other four aggregates.
Some of the affecting variables are congruent (ldan-pa'i 'du-byed) with the primary consciousness (rnam-shes) of the experience, such as positive and negative emotions, attention, and interest. Others are noncongruent affecting variables (ldan-min 'du-byed), such as habits. Congruent means sharing five features in common, such as the same focal object. Each moment of experience contains many items from this aggregate factor.
Aggregate of Primary Consciousness
The aggregate of primary consciousness (rnam-shes-kyi phung-po, aggregate of consciousness) comprises the six types of primary consciousness:
- Eye consciousness
- Ear consciousness
- Nose consciousness
- Tongue consciousness
- Body consciousness
- Mental consciousness.
Most Western cognitive theories discuss consciousness as a single factor that can cognize all categories of cognitive objects – sights, sounds, smells, tastes, physical sensations, and purely mental objects such as when thinking. In contrast, the scheme of five aggregate factors specifies different types of primary consciousness in terms of the cognitive sensor it relies on to arise.
Primary consciousness cognizes merely the essential nature (ngo-bo) or type of phenomenon that something is. For example, eye consciousness cognizes a sight as merely a sight.