A curious thing happens when I say that I study the Heart Sutra. My friends and colleagues will often ask if I have read such and such a book on it, usually a popular and/or religious book. Or worse they will recommend that I read a book they like. Most of my friends are well read and if interested in a subject are quite capable of consuming all the popular books available. And the assumption seems to be that studying the text is a matter of doing this. "Research" is reading the academic books. In this view scholarship appears to be an ability to summarise the ideas of other people.
But this is not what I do. I almost never read popular books on the Heart Sutra. And most of the academic books are so flawed that they make no positive contribution to my work. The Heart Sutra has been thoroughly misunderstood for about 1300 years. Broadly speaking, I do three kinds of work on the Heart Sutra: philology, history, and philosophy.
Philology is an account of what texts mean and why they mean that (and not something else). My contributions to philology of the Heart Sutra have been in two areas. I have noticed and corrected mistakes in Conze's Sanskrit edition, and I have contributed to establishing which language the Heart Sutra was composed in. The latter involved noticing and commenting on Chinese idioms in the Sanskrit text. I have stated that the Sanskrit Heart Sutra is a late 7th Century Chinese forgery, committed by someone with a working knowledge of Sanskrit but not of the Prajñāpāramitā genre in Sanskrit. I also showed that the famous phrase "form is emptiness" (rūpaṃ śūnyatā) had been deliberately changed from an original "appearance is an illusion" (rūpaṃ māyā) which could then be linked to the early Buddhist simile that "appearance is like an illusion" (rūpam māyopamaṃ). The change resulted in a statement that cannot be understood at face value. I have also suggested that the selection of the passages copied from Kumārajīva's Large Sutra may have been guided by popularity as some of them appear in inscriptions that predate Xuanzang by at least a century.
In terms of history I have published the first complete English-language description and translation of the Fangshan Stele, the earliest dated Heart Sutra (13 March 661). I related this to the legend of Xuanzang. I have also extended the historical narrative of the Heart Sutra as a Chinese text, helping to pin down the date of composition, identifying the Heart Sutra with the genre of "digest texts" (chāo jīng 抄經). And in particular, I have stressed that the received history of the text contains deliberate deceptions that hide the real history. One can still make out elements of the original history. We can tell the approximate year the Heart Sutra was composed (656 CE). We can say with some confidence that it was composed by Xuanzang.
Taking cues from Sue Hamilton and work on the language of the Heart Sutra by Huifeng (Matthew Orsborn) I have outlined a new philosophy of prajñāpāramitā which eschews the twisted metaphysics of (Nazi-sympathiser) D. T. Suzuki and his narcissistic acolyte Edward Conze. Neither man understood the first thing about prajñāpāramitā. I argue that the texts are primarily phenomenology and epistemological: i.e. concerned with experience and what can be learned from the cessation of experience. For example, I explain śūnyatā in this context as "the absence of sensory experience in samādhi". This occurs after the cessation (nirodha) of sensory experience due to practising the yoga of nonapprehension (anupalambhayogena), and results in a state that is without conditions (asaṃskṛta) and synonymous with extinction (nirvāṇa). In this state the apparatus of experience (skandhas) stops producing sense experience but leaves the meditator in a state of contentless awareness. This allows me to discuss Buddhist doctrines and attainments in terms entirely consistent with a modern philosophical Realism.
And none of this could be found in books. Most of it involves closely reading Sanskrit and Chinese versions of the text together and taking into account all the many variant readings in extant manuscripts and inscriptions. Moreover, none of it can yet be found in books. Although I have now published 10 articles in academic journals detailing my evidence, methods, and conclusions there is no book yet. Hopefully the book will come! But I'll be writing that book, not reading it.