The following is extracted from Wikipedia
In Buddhism, the four Great Elements (Pali: cattāro mahābhūtāni) are earth, water, fire and air. Mahābhūta is generally synonymous with catudhātu, which is Pāli for the “Four Elements.” In early Buddhism, the Four Elements are a basis for understanding that leads one through unbinding of ‘Rupa’ or materiality to the supreme state of pure ‘Emptiness’ or Nirvana.
In the Pali canon, the most basic elements are usually identified as four in number but, on occasion, a fifth and, to an even lesser extent, a sixth element may also be identified.
Four primary elements
In canonical texts, the four Great Elements refer to elements that are both “external” (that is, outside the body, such as a river) and “internal” (that is, of the body, such as blood). These elements are described as follows:
- Earth element (pruṭhavī-dhātu)
Earth element represents the quality of solidity or attractive forces. Any matter where attractive forces are in prominence (solid bodies) are called earth elements. Internal earth elements include head hair, body hair, nails, teeth, skin, flesh, sinews, bone, organs, intestinal material, etc.
- Water element (āpa-dhātu)
Water element represents the quality of liquidity or relative motion. Any matter where relative motion of particles is in prominence are called water elements. Internal water elements include bile, phlegm, pus, blood, sweat, fat, tears, nasal mucus, urine, semen, etc.
- Fire element (teja-dhātu)
Fire element represents the quality of heat or energy. Any matter where energy is in prominence are called fire elements. Internal fire elements include those bodily mechanisms that produce physical warmth, ageing, digestion, etc.
- Air (or wind) element (vāyu-dhātu)
Air element represents the quality of expansion or repulsive forces. Any matter where repulsive forces are in prominence are called air elements. Internal air elements includes air associated with the pulmonary system (for example, for breathing), the intestinal system (“winds in the belly and bowels”), etc.
Any entity that carry one or more of these qualities (attractive forces, repulsive forces, energy and relative motion) are called matter (rupa). The material world is considered to be nothing but a combination of these qualities arranged in space (akasa). The result of these qualities are the inputs to our five senses, color (varna) to the eyes, smell (gandha) to the nose, taste (rasa) to the tongue, sound (‘shabda’) to the ears, and touch, to the body. The matter that we perceive in our mind are just a mental interpretation of these qualities.
Fifth and sixth elements
In addition to the above four elements of underived matter, two other elements are occasionally found in the Pali Canon:
- Space element (ākāsa-dhātu)
Internal space elements includes bodily orifices such as the ears, nostrils, mouth, anus, etc.
See also: Prayer flag § Colour and order
- Consciousness element (viññāṇa-dhātu)
Described as “pure and bright” (parisuddhaṃ pariyodātaṃ), used to cognise the three feelings (vedana) of pleasure, pain and neither-pleasure-nor-pain, and the arising and passing of the sense contact (phassa) upon which these feelings are dependent.
According to the Abhidhamma Pitaka, the “space element” is identified as “secondary” or “derived” (upādā).
Sensory qualities, not substances
While in the Theravada tradition, as well as in the earliest texts, like the Pali Canon, rūpa (matter or form) is delineated as something external, that actually exists, in some of the later schools, like the Yogacara, or “Mind Only” school, and schools heavily influenced by this school, rupa means both materiality and sensibility—it signifies, for example, a tactile object both insofar as that object is tactile and that it can be sensed. In some of these schools, rūpa is not a materiality which can be separated or isolated from cognizance; such a non-empirical category is incongruous in the context of some schools of Mahayana and Vajrayana Buddhism. In the Yogacara view, rūpa is not a substratum or substance which has sensibility as a property. For this school, it functions as perceivable physicality and matter, or rūpa, is defined in its function; what it does, not what it is. As such, the four great elements are conceptual abstractions drawn from the sensorium. They are sensorial typologies, and are not metaphysically materialistic. From this perspective, they are not meant to give an account of matter as constitutive of external, mind-independent reality. This interpretation was hotly contested by some Madhyamaka thinkers like Chandrakirti.
As Four Fundamental Aspects, Not Rigidly Four Elements
Very few scholars of (virtual) meta-analysis (of Theravada Buddhism and science) adopt a broader view of the rest of Buddha’s concepts about the four mahābhūtas, which leads to an idea that they should not be rigidly translated to earth or solid, water or liquid, air or gas, and fire or plasma. Such speculation considers them as fundamental aspects of any physical object, definitely not very parts of a touchable object.
- Pathavī-dhātu should be density of any fundamental piece of mass; as soon as a mass exists in reality, it does take up a volume in space, and this is one of the four fundamental aspects. Although earth could have been mentioned by Buddha as the best example of this nature, any solid or liquid or gas would possess its own extent of this nature.
- Apo-dhātu or āpa-dhātu should be the combined nature of fluidity or viscosity, solubility and perhaps a few other similar features of any fundamental piece of mass. Although water could have been mentioned by Buddha as the best example of this nature, any solid or liquid or gas would possess its own extent of this nature.
- Vāyo-dhātu or vāyu-dhātu should be the nature of reactant force or pressure of any fundamental piece of object. This manifests itself in Newton’s third law of motion and Pascal’s law. Although air could have been mentioned by Buddha as the best example of this nature, any solid or liquid or gas would possess its own extent of this nature.
- Tejo-dhātu or teja-dhātu should simply be heat energy. Although some Buddhist texts contain two types of tejo: fire of heat and fire of (sheer) coldness, we nowadays understand that coldness is mere our interpretation of feeling something with less heat energy than the subject, any particle being scientifically not possible to have absolute zero of heat.
The Four Elements are used in Buddhist texts to both elucidate the concept of suffering (dukkha) and as an object of meditation. The earliest Buddhist texts explain that the four primary material elements are the sensory qualities solidity, fluidity, temperature, and mobility; their characterisation as earth, water, fire, and air, respectively, is declared an abstraction – instead of concentrating on the fact of material existence, one observes how a physical thing is sensed, felt, perceived.