When analysing a cup of coffee, a scientist might break it into solid (the cup), liquid (the coffee) and gas (the aroma). According to the Abhidhamma, a cup of coffee consists of rūpa such as hardness, roughness, heaviness, heat, visibility and odour. The Abhidhamma focus is on how the cup of coffee is impacting the senses. The focus of Buddhism is spiritual development and spiritual development involves the mind, so the Abhidhamma approach uses the mind as the starting point. This is why in the example of the cup of coffee, the Abhidhamma focuses on how the object impacts the senses.
The word “element” tells us to focus on the properties rather than the literal meaning of earth, water, fire or air. The Four Great Elements are experiences, Ultimate Realities, not concepts. The ancient Greeks and others used the same four elements to describe the composition of the world, but generally adopted the literal or symbolic meaning rather than Buddhist approach that focuses on properties. Rūpa are not abstract categories; they are the realities that appear in daily life.
Earth-element is the experience of hardness or softness, roughness or smoothness, heaviness or lightness. Here are some exercises to experience Earth-element. Be aware of hardness in the teeth; bite them together and feel how hard they are. Be aware of softness by pressing your tongue against the inside of your lips to feel its softness. Rub your tongue over the edge of your teeth or brush your hand over the skin of your arm and feel roughness. Experience smoothness by wetting your lips and rubbing your tongue over them, from side to side. Place one hand on top of the other in your lap and feel the heaviness of the top hand, or feel the heaviness of the head by bending it forward. Look for lightness by wagging a finger up and down and feeling its lightness. If something floats in the ocean, it is because the Earth-element in the ocean supports it. If a balloon floats, it is because the Earth-element in the air supports it.
Water-element is flowing and cohesion. Flowing and cohesion cannot be experienced, but it can be understood by the mind. To understand flowing, imagine the blood flowing through the blood vessels, the air flowing into the lungs, or heat flowing throughout the body. To understand cohesion, consider how the body is held together by the skin, flesh, and sinews. The blood is held inside by the skin, like water in a balloon. Without cohesion the body would fall into separate pieces. The force of gravity which keeps the body stuck to the earth is also cohesion.
Fire-element is the experience of heat and coldness. It is usually very easy to look for heat throughout the body. Feel the coldness of the breath as it enters the nostrils and then understand it throughout the body. The function of Fire-element is to ripen, mature, age and burn up. The Fire-element also aids in digestion.
Air-element is the experience of supporting and pushing. To experience supporting, relax your back so your body bends forward. Then straighten it and keep it straight. The force that keeps the body straight is supporting. The supporting Air-element ensures that all things maintain their shape and do not collapse. To experience pushing, be aware through the sense of touch of pushing in the centre of the head as you breathe in and out or experience the pushing as the chest expands or as the abdomen moves when breathing. Wherever there is movement, there is pushing. Though the function of Air-element is causing motion, movement is not the alteration between two stages of the same rūpa, but rather as the disappearance of one rūpa and the immediate emergence in its place of another rūpa. For example, in a movie theatre, many static frames are projected onto the screen each second and a sense of movement is created.
All groups of rūpa include the Four Great Elements. In a stone and a snowflake, the Four Great Elements exist in equal proportion, but of varying intensity. The intensity and the Mental Factor of Attention determine which experience body-consciousness recognizes first. For example, when you put your hand in water, the softness felt is Earth-element, the coolness felt is Fire-element and the pressure felt is Air-element. If the water is cold, then the Fire-element may be experienced first. If there is attention being paid to the sensation of pressure, then Air-element may be experienced first.