Shūnyam is the formal Sanskrit for Śūnya in common-speak. Etymologically, Shūnyam originate in the notion of hollowness, of ‘Empty Inside’.
The term ‘Empty’ or ‘Null’ as used in English translations of Shūnyam originate directly from the vocabulary of Classical Logic as does the word ‘Form’ as used in the Heart Sutra. [Although no guru, fee-speaker or book-writer I have met is aware of this root, which might explain their wildly creative interpretations of these two terms.]
Shūnyam itself is not to be confounded with the numerous versions of Śūnya with a suffix that evolved in the regional Dharmic literatures well into the 10th Century [ŚūnyaBrahman, ŚūnyaPurusha et al]. Or the selective use of the term ‘Emptiness’ in others [Kashmiri Shaivism, the Southern Bhairava et al]
The later derivative construct of Shūnyathā, a pivotal term in the ‘Heart Sūtra’ found its inspiration in an established earlier divide: Táthātā and Tát. And as with Shūnya, there are a variety of definitions of Shūnyathā to pick from beginning with the Theravada and reaching into all variants of the Mahayana.
What’s the difference? Táthātā, typically translated into English as ‘That-ness’ [also as Suchness, Thusness] is the abstraction of Tát [‘That’]. The problem is that you cannot abstract ‘That’ which has already gone well beyond such distinctions as ‘Abstract and Concrete’. It can only be abstracted by one who doesn’t understand its intent.
If it had any other purpose it was to differentiate the philosophical substance of ‘That’ from its routine grammatical chores. This would have been entirely legitimate. But it was rarely used in this service and very soon after its construction [and predictably so], ‘Thatness’ took on a philosophical life of its own.
What happened with Tát: Táthātā is exactly what happened much later in the construction of the distinction: Shūnyam: Shūnyathā.
Again and as before, one does not abstract ‘True Nothing’. Shūnyam itself is the leap from the limit of abstraction. The attempt at abstraction is only done by one who does not comprehend its intent or meaning.
But the derivative extension of Shūnyathā continued to firmly retain the original Logical Form of its parent. In fact it’s most consistent definition in the higher texts has been ShūnyathāShūnyathā: ‘The Emptiness of Emptiness itself’, a full-blown Self-Eating Expression.
The result was consequential. Depending on the source, Shūnyathā has been interpreted both as a synonym for a conceptualized Shūnyam and otherwise as a mystic expression for some special capture of Awareness, Consciousness, or the Whole.
Without getting into the ponderous details here, the later extensions, principally the Madhyamaka, pivot off the Principle Of Co-Dependence without reaching into the Axioms of Sight and ‘Self”, in parallel to the Vedanthic stop at ‘Being: Consciousness’.
Following the release of the posted article [‘Venice, London And The Earliest Dated Dot’], a writer made the sharp observation cited below on the origin of the symbol. [I forget his name; drop me a note if you recognize this piece.]
‘The concept of zero seems intuitive, but that’s because we’re already familiar with it. There’s a big conceptual leap between saying ‘there are no apples on this tree’ to saying ‘this tree has zero apples on it.’
Both ‘No Apples’ and ‘Zero Apples’ are conceptual extracts, neither being Shūnyam [True Nothing]. But the above is a helpful distinction and it can be made more visible.
Around 600 CE, Chandrakirti, an articulate spokesman for the Mādhyamika school which claimed itself a dialectic, itself holding ‘No views of its own’, gave this illustration of one who retains a ‘View’ of Absence [i.e. an Idea, a conceptual elaboration].
‘It is as if I ask a shopkeeper:’What do you have to sell?’. And he replies: ‘I have nothing to sell’. And I say: ‘Oh, fine! That will do. Sell me this nothing then.‘
The claim: ‘We have no views!’, is problematic and ultimately undermines the Mādhyamaka school itself. Grounded exclusively in the early Buddhist Doctrines of Co-Dependency, in Shūnyathā, it is an unwound Self-Eating Expression, a stopping short of the terminus.
But that does not take away from Chandrakirti’s illustration or the writer’s observation.
There are numerous translations of varying quality available of the the Hridaya [‘Heart’] Sūtra, many on the Net. I suggest staying with a respected and tested version such as that of the Nalanda Translation Committee.