It is said that the world consists of three elements, that pure fire, pure water and pure earth make up everything. The wholly pure elements, however, perhaps exist only as a cosmic principium, a principle, while in the reality of matter they exist as compound blends, embedded in one another.
Divide the three elements in half, then divide one half of each into two equal parts, then mix the quarter of each element with the remainder of the other two, and so you obtain the threefold-mixed elements.
These blended, mixed elements suggest the composite structure of matter. The elements of pure fire, pure water and pure earth are halved. One half of each remains unmixed, and the other half is halved again. Thus fire, water and earth are each made up of three parts, one half and two quarters. The mixed fire element is half pure fire, a quarter water and a quarter earth. The mixed water element is half pure water, a quarter fire and the other quarter earth, while the mixed earth element is half pure earth, a quarter fire and a quarter water.
The secret teachings carry this threefold idea further, and discover a similar law in the metabolism of man as well.
The food that is consumed (transformed earth) becomes threefold – its coarsest part becomes waste, the good of it becomes flesh, and the finest of it becomes mind.
The water that is consumed becomes threefold – its coarsest part becomes urine, the good of it becomes blood, and the finest of it becomes breath.
The fire that is consumed (in the form of oil or butter) becomes threefold – its coarsest part becomes bone, the good of it becomes marrow, and the finest of it becomes speech.
Verily I say to you, my dear, of food the mind is made, of water the breath, and of fire speech. (Chandogya Upanishad 6.5.1–4.)
Yet the triple modification of earth, fire and water is not to be confused with the process by which the elements are divided into three. It is not that in earth (that is, in food) the pure earth element becomes excrement, its water part flesh and its fire part mind; rather, consumed earth is eliminated in three ways: as excrement, as flesh and as mind. In the same way the organism rids itself of the water it consumes, which becomes urine, blood and breath, and of fire, which becomes bone, marrow and speech.
The threefold division and mixing of the elements resembles the fivefold division of Vedanta philosophy, according to which the five compound elements (earth, water, fire, air and ether) arise from the five pure elements (scent, taste, heat, form and sound) through a division and mixing like the one above.
Other sources hold that the human organism too consists of five elements – earth, water, fire, air and ether – its solid parts being of earth nature, its fluids of water essence, while the heat of the body is fire, its lungs air, and its cavities (such as the frontal sinus) ether. (Garbha Upanishad 1.)
Fire, becoming speech, settled in his mouth. Air, becoming breath, settled in his nostrils. The Sun, becoming sight, settled in his eyes. The quarters, becoming hearing, settled in his ears. Plants and trees, becoming hair, settled in his skin. The Moon, becoming mind, settled in his heart. Death, becoming the out-breath, settled in his navel. Water, becoming seed, settled in his organ of generation. (Aitareya Upanishad 1.2.4.)
And God chose man as a dwelling, to become action within him…