In the Bahudhàtuka Sutta (MN 115), the Buddha explains that there are actually eighteen physical and mental elements. These are six triads of elements where each triad is composed of a sense object (the external sense bases), a sense organ (the internal sense bases), and the six related sense-consciousnesses (viññāṇa):
1. There is the element of the eyes as a visual organ
2. The form element as an objective visual
3. Eye-consciousness as the cognizance of the form perceived by the eyes
4. The ear element, or the ears as auditory organs
5. The element of sounds or audible objects
6. Ear-consciousness as the cognizance of the sounds perceived by the ears
7. The nose element as the olfactory organ
8. The element of aromas, scents, odors, fragrances, etc.
9. The nose-consciousness as the cognizance of the oflactive objects sensed by the nose
10. The tongue element as the gustatory organ
11. The elements of tastes, flavors, etc.
12. The tongue-consciousness as the cognizance of gustation sensed by the tongue
13. The body element as the tactile organ
14. The tangible element of touch, contact, etc.
15. Body-consciousness as the cognizance of the tangible objects sensed through body-contact
16. The mind element as consciousness and discernment
17. The element of mental objects (mano-dhātu) such as intellect, ideas, thought-processes, etc.
18. The mind-consciousness element (mano-viññāna-dhātu) as cognizance itself, or that which discerns
As a more concise, alternative description, the Buddha condensed these eighteen elements into only six descriptive natural elements. These include the four great elements that most people are familiar with – earth, air/wind, sea/water, and fire. Some traditions include a fifth element such as akasha/aether/sky/space/etc. These four classical elements (dhātu or mahā-bhūta), as well as the fifth, are also found within Buddhism. There is also a sixth element, which is consciousness. However, these elements themselves are more properly understood to be categories of sensorial qualities which are used to relate to the sensible physical world, rather than as substances. Therefore, these six elements can be understood as:
1. The Earth Element, or everything solid (pathavī) in the body, such as sense organs, hairs, teeth, tendons, bones, etc.
2. The Water Element, or all that is liquid (āpo) within the body. This is quite a bit, considering that up to 60% of the human body is water, while the brain itself is composed of about 70% water.
3. The Fire Element, or the heat (tejo) energy in the body. This can be related to body temperature, metabolism, temper, etc.
4. The Air Element, or everything internal that is in like wind (i.e. in motion; vāyo). This quite obviously applies to the air we breathe, but it can also relate to other things as well such as blood flow.
5. The Space Element, or the aether (ākāsa) constituted by the physical elements. This can be more easily comprehended as the bodily orifices such as the mouth, ears, nostrils, etc.
6. The Mind Element, or the emergent consciousness (viññāna) that arises from the other elements, by which they become conscious of themselves. This is cognizance, or that which discerns the three feelings (vedanā) of pleasure, pain and neither-pleasure-nor-pain, and the arising and passing of the sense contact (phassa) upon which these feelings are dependent.
So it is easy to see how the six elements make for an easier mindfulness practice. There are of course other examples given which can be used for understanding the elements, but for now we will focus on this formula of six elements.
There was once a wandering aesthetic named Pukkusati who went traveling to search out and meet the Buddha. However, he had never seen the Buddha before so how would he even be able to recognize him once he did? Well, he wasn’t. He was only able to realize his mistake after the Buddha related to him the six properties/elements, six media of sensory contact, eighteen considerations, and the four determinations.
However, the main point of the six element practice is to note that how each is an ever-changing, temporal process, rather than a static, abiding quality or substance. Each element, that is: solidity, fluidity, airiness, aether, and consciousness, makes up our body but none of them can be identified as an intrinsic whole in their own right. They are all empty of inherent existence as they are all dependently co-arisen processes.
Therefore, all things perceived by the these six elements (or even just one of them) are actually unfit for identification with a “self”/”ego” or “soul” (atta) since they are impermanent (anicca) – and because there is anicca there is dukkha. The mark of not-self (anatta) states that one should regard the six elements with right discernment as, “This is not mine, this is not my self, this is not what I am.” Realizing this one grows weary and disenchanted with the each of these elements, letting go of attachment to each by progression through the jhanas, until there is only consciousness which discerns pleasure, pain and neither-pleasure-nor-pain.
With the cessation of the very sensory contact which is to be felt as pleasure, pain and neither-pleasure-nor-pain, the concomitant feeling of said pleasure, pain and neither-pleasure-nor-pain also ceases. That is, consciousness is stilled. When this occurs, only equanimity will remain: pure and bright, pliant, malleable, and luminous. This can lead one to Nibbāna (Skt. Nirvāṇa), in which “birth is exhausted,the holy life fulfilled, the task done” and there is “nothing more of this becoming.”