Five Skandhas
Skandha is a Sanskrit word meaning 'heap, pile or aggregate.' The five skandhas are 1) form, 2) feeling, 3) cognition, 4) formations, and 5) consciousness.

The Buddha illustrated his teaching about the skandhas by using five small piles —heaps —of different grains. The skandhas are general divisions for categorizing all phenomena in the conditioned world. Because they include within them all transitory, impermanent phenomena, they are an important tool for understanding the Buddhist doctrine of no self. If one analyzes all aspects of what one feels to be one’s “self,” one finds that all fall within the scope of the Five Skandhas.

Form
And why, brethren, do ye say body [i.e., form]? One is affected, brethren. That is why the word “body” is used. Affected by what? Affected by touch of cold and heat, of hunger and thirst, of gnats, mosquitos, wind and sun and snakes. One is affected, brethren. That is why we say “body.” (Rhys Davids, tr. Kindred Sayings III 72-73)

“What is form? The body is included among the form-dharmas; since it is form, it is called the “form body.” Your form body has an appearance, but when you seek for its origin you will find that it is empty.… When the Four Great Elements, namely earth, water, fire, and wind, unite, the body comes into being. This is what is meant by having a form. Working together the elements establish a corporation. The corporation comes into being from the four conditioned causes: earth, which is characterized by solidity and durability; water, which is characterized by moisture; fire, which is characterized by warmth; wind, which is characterized by movement. When the four conditioned causes disperse, each has a place to which it returns; therefore, the body becomes empty.” (HS 44-45)

Feeling
“Once the body manifests, it likes pleasurable feelings. There are three kinds of feelings, which correspond to the three kinds of suffering: feelings of suffering; feelings of happiness; feelings which are characterized by neither suffering nor happiness.” (HS 45)

Cognition
And why, brethren, do ye say “perception [another translation of saṃjṅā]”? One perceives, brethren. That is why the word “perception” is used. Perceives what? Perceives blue-green, perceives yellow, or red, or white. One perceives, brethren. That is why the word “perception” is used. (Kindred Sayings III 73)

Cognition is the differentiation and identification of objects both physical and mental. Therefore, it includes both higher perceptual functions and thinking processes, including those of language.

“As for cognition, you certainly must have (the need for) false thoughts if you want enjoyment. You can’t be without it. ‘How can I think of a way to buy a car? How can I buy a beautiful home? How can I think of a way to buy a yacht? An airplane?’ Your false thoughts fly back and forth and your hair turns white. Why? It turns white from false thinking.” (HS 46)
When you are awake, your mind thinks. When you are asleep, you dream. Thus your thinking [another translation of saṃjṅā] is stirred to perceive false situations . (SS VIII 377)

Formations
Formations refer to both conscious and unconscious volitional forces, including:
1) conscious intentions or acts of will, the most important category of this skandha
2) innate predispositions (karma from past lives)
3) unconscious forces having to do with basic life functions, nourishment, and growth

“When you lie in bed at night, you have a thousand plans.…Sometimes you get up early and act on them. Sometimes sleeping seems nice, and you just sleep. Formations are basically the acting out of karma, that is, really acting upon your false thinking.” (HS 46)


And why, brethren, do ye say consciousness? One is conscious, brethren. Therefore, the word “consciousness” is used. Conscious of what? Of (flavours) sour or bitter; acrid or sweet; alkaline or non-alkaline; saline or non-saline. One is conscious, brethren. That is why the word “consciousness” is used. (Kindred Sayings III 74)

It is like rapidly flowing water that appears to be still on the surface. Due to its speed you don’t perceive the flow, but that does not mean it is not flowing. (SS VIII 384)

“The skandha of consciousness involves the making of distinctions. It discriminates, considers, and seeks advantages from circumstances.” (SS III 22)

Consciousness is the subtle basis of feeling, cognition, and formations. It consists of a subtle distinction-making awareness that distinguishes awareness from the objects of awareness. It is a flux.


Commentary

The mind is like an artist
Who can paint the entire world.
From this the five skandhas arise
As well as all dharmas. (FAS Ch20, HYSC 30:63)

The Five
Body [i.e., form], brethren, is impermanent. What is impermanent, that is suffering. What is suffering, that is not the Self. What is not the Self, “that is not mine, that am not I, that is not the Self of me.” This is the way one should regard things as they really are, by right insight. So likewise with regard to feeling, perception, the activities, consciousness. So seeing, brethren, the well-taught Ariyan [i.e., noble] disciple feels disgust at body, at feeling, perception, the activities and consciousness. Feeling disgust he is repelled: by repulsion he is released; by that release set free, knowledge arises: “in the freed man is the free thing,” and he knows: ‘destroyed is rebirth; lived is the righteous life; done is the task; for life in these conditions there is no hereafter.” (Kindred Sayings III 68-69)

The skandha of form is like a mass of foam, because, when taken hold of, it cannot be kept together (in the hand); feeling is like a bubble because, as lasting only for a moment, it is impermanent; perception (cognition) is like a mirage, because it is misled by the thirst of craving; the impulses (formations) are like a plantain tree because, when (the leaf-sheaths) are taken away, no core remains; consciousness is like a dream, because it takes hold of what deceives. Therefore, the five skandhas have no self, (and they contain) no person (pudgala), no living being, no living soul, no personality and no manhood (puruṣa).… (Conze, tr. Arya-prajñā-pāramitā-hṛdaya-tīkā 54)

“When you break through all five skandhas, and are no longer deluded by them, you can ‘cross beyond all suffering.’ You can then put an end to all bitterness. Seeing that the Five Skandhas are all empty is getting rid of the attachment to self.” (LY II 104)


Chinese / Sanskrit / Pali Terms

五陰/五蘊 ; skandha ; khandhas

‘heap, pile, or aggregate.’