The following terms are interchangeable depending upon circumstance, and the Ch’an masters made use of them in a more or less free-flowing style, but do not let their apparent ‘casual’ approach to Buddhist terminology mislead you as each term possesses a distinct and startling meaning, designed to cause such a ‘shock’ to the deluded system, that it is immediately and radically transformed here and now:
1 Dharmakaya (法身 – Fa Shen), or ‘Truth Body’ represents the pure and unsullied state of reality that although existing within the world, remains entirely unpolluted by it. It is not ‘created’, nor does it ‘diminish’ in anyway. It has no shape, and is limitless. It stands for nirvana within samsara – and its realisation is non-conditioned. The illusion is that samsara exists independently of nirvana, and that nirvana is somekind of ‘superimposed’ spiritual state over delusion. This is why Hui Neng says (in the Altar Sutra) that when the six sense-roots are purified of delusion – despite still being in the world, they remain ‘unsullied’ by their daily association.
2) Cittabhumi [心地 – Xin Di), or ‘Mind Ground’ signifies the psychological fabric from which all perception emerges and returns to. The process of ’emerging’ and ‘passing away’ is a correct to observe – but is an illusion in the over-all scheme of things. When the mind is confused through identification with dualistic interpretations, no sense of perception can be made as it manifests as a jumbled cascade. When the surface mind is quietened through meditation or enlightened interaction – its ’empty’ nature can be truly perceived – as if for the first time. As all is ‘non-substantial’ and free of any independent existence, the jumbled mind appears to be ’empty’ and ‘still’. This is an important stage of developed awareness. In reality, however, the empty mind ground is the root of all perception AND non-perception, and so the realisation of ’emptiness’ and ‘stillness’ must also return to it. This is not nihilism or creationism – both are imply another duality that must be pursued to their manifesting root.
3) Sunyata (空 – Kong), or Emptiness’ denotes the reality of things that appear to be ‘substantial’ and ‘independently’ real to the undeveloped mind and its senses. Emptiness is not ‘nothingness’ and must never be confused with it. Non-substantiality is not a negation of existence, but rather a clarification of how things actually are in reality. Therefore, emptiness is also considered ’empty’ of ’emptiness’. This does not go beyond Nagarjuna’s tetralemma – or ‘four part logic’:
1) All exists.
2) All does not exist.
3) All exists and does not exist.
4) All neither exists nor does not exist.
Nagarjuna – who read virtually all the known Buddhist sutras of his time, deduced that the Buddha was teaching from this philosophical position – which by necessity – has no position.