Shortly after his attainment of awakening, the Buddha was seated with his five first disciples, and he spoke to them about the content of their everyday experience. When doing this, he classified all that they experience into five ‘heaps’ (Pali khandhas; Sanskrit skandhas) of similar kinds of things that we experience, or five ‘aggregates’ that make up our sense of the world:

1. Physical form (Pali/Sanskrit rūpa). Our sense of ourselves as beings with bodies that move around and exist in the world.

2. Feelings (Pali/Sanskrit vedanā). Our sense of whether something is pleasant or unpleasant to us (or neither).

3. Ideas (Pali saññā; Sanskrit saṃjñā). The thoughts that we have that make sense of both what we perceive (see, hear, touch and so on).

4. Attitudes (Pali saṅkhāra; Sanskrit saṃskāra). Our basic opinions about things, including our attraction to them, or repulsion from them.

5. Perception (Pali viññana; Sanskrit vijñāna). What our senses are detecting at every moment: what we see, hear, smell, taste, touch and also, when we reflect on these things, what we think.

The Buddha implied that this provided a good account of all things that we experience: if we did not experience any of these things – had no physical body, no feelings, no ideas, no attitudes, and did not perceive anything – it would be hard to say that we even existed.

The Buddha asked his audience to think about each of these five types of experience. He suggested that none of these five things should be considered to be our “self” – none of them is what I really, truly am – and he proved this to his monks by asking them to think about it themselves.

“Monks,” said the Buddha, “what do you think about your physical form? Is it something that is permanent, or is it impermanent?”

The monks realized that nothing in their body remained the same: it had been changing ever since they had been alive, growing from childhood into adulthood, but also in subtle ways ever since. As they grew old, their bodies would change even more, and eventually they would die.

“It is impermanent, sir” answered the monks. “And if it is impermanent,” continued the Buddha, “does this mean that your body is something that you find satisfying, or is it unsatisfying?”

The monks thought again, and reflected that anything that is impermanent, and is changing, and ultimately will pass away, cannot be something that is really, truly satisfying.

“It is unsatisfying, sir” the monks admitted.

“And so,” continued the Buddha, still further, “is what is impermanent, and so unsatisfying because it is changing, something that you would consider to be really you, or what is really yours?”

“No, sir, we would not…”

So the body, the monks concluded, is not what they really are, not their true self, or something that they should consider particularly important or precious. The Buddha then asked the same questions about the other four “heaps” of their experience, and the monks had similar thoughts. Feelings are constantly changing, so none of these feelings can be what the self really is, or where the self can be found. Ideas certainly change, so the same is true there. Attitudes obviously change, as we come to like or dislike different things at different times. And our perceptions? These are changing constantly, as we see, and hear, and smell, and taste, and touch, and think different things from moment to moment: nothing anywhere in my physical person, or in my mind, stays the same – so where, in all of this, is something to consider and hold to as “my self”?

The monks realized that there was nothing in their experience to which they should cling: although these five types of experience were all that they knew, they should not think of any of them as being where to find something impermanent, or satisfying, or apart from change.

Each of us are changing constantly, and so there is nothing in us that is permanent or fixed. The monks had a sense of calm, realizing that one of their problems was assuming that any of these types of experience was particularly special or precious, and they attained nirvana.