The hua tou method is an effective spiritual technique designed to induce in the Ch’an practitioner nothing short than the experience of complete enlightenment itself. As a distinct method, it probably has its origins within the Surangama Sutra which was translated into Chinese in 705 CE. The key phrase found within this sutra is spoken by the bodhisattva Avalokitesvara (Guan Yin):
‘At first by directing the hearing (ear) into the stream (Of meditation) this organ from its object was detached.
By wiping out (the concept of) both sound and stream entry,
Both disturbance and stillness, Were clearly non-existent.
Thus advancing step by step,
Both hearing and its object ceased;
But I did not stay where they ended.’
Many Western sources, (following the lead of many of their Chinese scholarly counter-parts), attribute either the founding of the hua tou method, or its development, to the Song Dynasty Ch’an master Dahui Zonggao (大慧宗杲 1089–1163), who is famous for his Ch’an letter writing tradition, and made extensive use of a combined gong-an – hua tou method. The attributing of a unique and distinct position for Dahui with regard to the hua tou method is, however, problematic. Morten Schlutter, for instance, makes the following poignant observations with regard to Dahui, and the unique attributes ascribed to him with regard the hua tou method, often referred to as ‘kan hua’ (看話 – ‘look word’) when discussing Dahui:
‘Dahui’s name is inextricably connected to what has come to be known as kanhua Chan, literally “Chan of observing the key phrase,” although Dahui himself did not give it a name. This approach to Chan practice involves focusing intensely on the crucial phrase, or “punch line” (the huatou), of a gongan. Kanhua practice has therefore often been referred to as “gongan (or koan) introspection by Westerner writers. As discussed in Chapter 1, gongan are highly enigmatic and frequently startling or even shocking stories about legendary Chan masters’ interactions with disciples and other interlocutors, usually taken from the records of “encounter dialogues” found in the transmission histories. Encounter dialogue, with its disruptive language and seeming non sequiturs, has come to be considered the hallmark of Chan literature (although, in fact, Chan literature includes a wide range of different genres and styles of writing).
Schlutter ascribes two important footnotes to the above paragraph that are worth quoting in their entirety:
’27. In a discussion of Dahui’s use of the gongan, Robert Buswell writes that Dahui “called this new approach to meditation kan-hua Chan.” “Short-Cut Approach,” 347. However, Dahui never used the term “kanhua Chan” and did not present his use of the gongan in meditation as an innovation, although it clearly was. In fact, the term “kanhua Chan” cannot be found in any premodern work, and it seems to have been first coined by Japanese researchers.
28. The word “huatou” seems often, both before and after Dahui, to have been used synonymous with gongan, although Dahui himself clearly distinguished the two.’
These facts demonstrate that master Dahui did not refer to his own enlightening method as either a ‘hua tou’, or indeed a ‘kan hua’, and did not view what he was doing as some thing ‘new’ and ‘original’. In fact, the impression one gets from Dahui is that he is following an older tradition that has been forgotten by those around him. For instance, this is how Dahui explains meditation to Fu Li-shen:
‘Both torpor and excitation were condemned by the former sages. When sitting quietly, as soon as you feel the presence of either of these two diseases, just bring up the saying, “A dog has no Buddha-nature.” Don’t exert effort to push away these two kinds of disease – just be peaceful and still right there. Over a long time, as you become aware of saving power, this is the place where you gain power. Nor do you have to engage in quiet meditation – this itself is meditation.’
Certainly this would be true, if the date of the presence of the Surangama Sutra (705 CE) is taken into account. Even if it were not, the fact still remains that the gong-an and hua tou methods were existent and in use prior to Dahui’s life-time. Scholars such as Stuart Lachs, for instance, acknowledge that Dahui did not invent the hua tou, but nevertheless continues the trend of the ascription of ‘specialness’ to Dahui’s enlightening method, in this instance, the formulating of a distinct Ch’an methodology for the Ch’an School. Despite the obvious collection of reliable academic information, neither Schlutter, Buswell, nor Lachs mention the Surangama Sutra in their respective analysis of the development of the hua tou method. Master Xu Yun (1840-1959), in his Dharma Discourse delivered at the Jade Buddha Monastery in 1953/54, does not mention master Dahui, but explains that it was in fact the Pure Land School that first utilised this method (and not the Ch’an School). The Pure Land practitioners chanted the Buddha’s name continuously, but the Pure Land masters noticed that the repeating was shallow and ineffective. To remedy this, (and presumably following Avalokitesvara’s advice found in the Surangama Sutra), the Pure Land practitioners were encouraged to question ‘Who is repeating the Buddha’s name?’ Master Xu Yun states that the Ch’an School had also adopted this method due to changing times, so that the effects of dull karmic roots and excessive sensory stimulation of the modern era could be over-come through spiritual training. This method was used to augment the Ch’an practice of the reliance upon enlightened exchanges – known as ‘gong-an’ – between masters and students. In this respect, master Xu Yun advocated the use of both the gong-an and the hua-tou method. The gong-an is a recorded conversation between a Ch’an master and a student. It is not just any old interaction, but one pregnant with significant meaning. Indeed, such is the importance of the spiritual import that merely encountering the recorded words of its detail is enough to illicit a breakthrough, beyond the surface clutter of the mind. In Chinese Ch’an, the gong-an practice consists of a direct encountering with the Mind Ground, without the cultural formality usually associated with the Japanese Zen/Ch’an tradition. The words of the gong-an, although embodying the spiritual content, are, nevertheless quite irrelevant to the experience they enable, and should be dropped as soon as they are picked up. The hua tou method, by comparison, is a method that focuses the mind firmly within, and away from the confusion of the senses and sense data. Like a psychic drill, it uses a concerted ‘will’ through asking a question that begins with the word ‘who’? Any sentence will do, as long as the question is permanently held firmly in the mind. Xu Yun is known to have used the hua tou ‘Who is dragging this corpse around?’, whilst master Han Shan used the hua tou ‘Who is hearing?’ The hua tou method follows the technical advice given by Guan Yin (i.e. ‘Avalokitesvara bodhisattva’), and found within the Surangama Sutra. Essentially this states that by focusing upon the organ of the ear, and turning the function of hearing back to its empty (sunyata) source, the state of enlightenment can be achieved. If the mind, whilst turning back toward its essence, starts discriminating and thinking ‘away’ from this objective, the method of the hua-tou (word-head) is lost, and instead has been supplanted by the error of hua-wei (word-end), whereby the discriminating mind has triumphed over the meditative method and has become entwined in the tails of words, as if swinging from one to the other, with no spiritual benefit. It should be noted, however, that the early Ch’an practitioners did not need the gong-an or hua-tou methods. Merely being shown the mind essence through a word or action was enough for the master to reveal the Mind Ground and for the student to instantaneously perceive directly, (indeed, it is these stories that form the basis for the many gong-an collections that exist) without recourse to any intermediate device, but as times changed, the masters found that students often required some kind of expedient method to assist the transformative process.
To understand the hua tou method, it is important to understand the Chinese ideograms that comprise the concept:
The ‘話頭’ (hua tou): 話 (hua4) is written to designate the spoken word, as in a speech or conversation, here it carries the meaning of ‘word’. 頭 (tou2) denotes a chief or instigator of plans or rituals. It refers here to ‘head’, or ‘top’, but is used in this context to refer to the ‘originator’.
Therefore, 話頭 (hua-tou) refers to the practice of realising the origin or empty essence of thought, as it manifests in the mind as ‘words’. The error of falling into ‘word-end’ contemplation is a common failing, and involves the mind simply following the deluded, internal chatter:
The ‘word-end’ 話尾 (hua wei): 話 (hua4) is written to designate the spoken word, as in a speech or conversation, here it carries the meaning of ‘word’. 尾 (wei3) is written as a sitting person with long hair down the back – which resembles a ‘tail’. Therefore, 話尾 (hua-wei) refers to the essence of the thought being lost, when this happens, all that is left is its inconsequential ‘tail’.
Master Xu Yun explains that above the doorway of every Ch’an meditation hall are written the words ‘照顧話頭!’ – or ‘Zhao gu hua-tou’!
In pinyin ‘照’ (Zhao4) is written as a fire that spreads light. It carries the meaning of ‘to look at’ with ‘care and attention’. ‘顧’ (Gu4) refers to ‘gazing’ or ‘looking’ at something and is written to represent a human head. Therefore the Chinese term Zhao gu – in this context refers to the act of turning the mind’s eye inward and in the process shedding light on the workings of the mind.
Through holding the hua tou, and caring for it appropriately, the light of wisdom (prajna) will appear, and the Mind Ground will be fully realised without error or hindrance, here and now. Although the Chinese term ‘hua tou’ (word head) seems esoteric due to the word structure used in translation, it is really quite a practical technique. This technique integrates both vipassana and samatha into one concentrated technique – in this regard it does not go beyond the Buddha’s teachings upon meditation. Of course, in its assessment many forget the corresponding notion of ‘hua wei’, or ‘word tail’. The hua tou turns the mind (as a sense organ) back upon itself so that with repeated enquiry, the mind’s essence is realised. All the sense organs, regardless of their distinctive sensory function, emerge from exactly the same ‘empty’ (sunya) base, and therefore the return of one sense to its base is the automatic return of all senses to the original base. It is the deep questioning of the word ‘Who?’ that is the most important factor – Who is hearing?, Who is writing?, Who is dragging this body around?, etc. It is the enquiry that is the hua tou, rather than the content of its structure. Whatever hua tou is used, the focusing of the mind upon the question brings the thoughts into one single stream, from their previously scattered condition. Then all the thoughts, as they emerge from the empty base – regardless of their nature and content become immediately transformed and channelled into the hua tou. Therefore it is true to say that good, neutral and bad thoughts are immediately incorporated into the spiritual struggle without exception or exclusion. In this state the mind experiences a sense of ‘oneness’, or ‘togetherness’, as opposed to its usual disparate and scattered nature. This is the beginning level. Further dedicated enquiry continues to gather and transform emerging thought regardless of its nature until the ‘gap’ between each thought is clearly perceived. This ‘gap’ manifests as a type of void – albeit relative, and two dimensional. This void can be entered and left at will during meditation practice – but it is only the head that is empty, as all the thoughts and thought streams have ceased due to the perception of the ‘gap’ between the thoughts. It is a marvellous time of mental peace and quietitude and although ranking the immutable is impossible, this stage may be described as ‘intermediate’. A further period of training is required. The Ch’an teacher assists this process by engaging the intellect of the student so that it is continuously stimulated in away that returns it to its essence. The student assists this process through the self-study of hua tou. Following the thoughts, instead of returning them to their empty base is called ‘hua wei’. It is a human habit that is very difficult to prevent – human beings literally become ‘lost’ in thought whilst trying to get to grips with the facility of ‘thinking’ itself. The gong-an is a method of interaction designed to reveal the empty essence of the intellect to itself in an instantaneous manner. If the intellect engages the gong-an, the gong-an is seen as illogical and pointless. In the old days the Ch’an masters were brutally compassionate and when gongan did not work they developed the hua tou practice. The gong-an and hua tou methods merge all the Buddha’s teachings on meditation together into one succinct technique that any one can practice regardless of expedient karmic circumstance. This is how Charles Luk (1898-1978) explains the hua tou practice:
‘When men were attached to material things, people of high spirituality became rare. The masters were then obliged to devise a poison-against-poison method called the hua t’ou which consists of the giving rise to a feeling of doubt (yi-qing – ‘doubting mind’) about WHO the seeker of Enlightenment is. Emphasis is on the word WHO which supports this vital doubt which comes from the student’s eagerness to know that which practices the Dharma. He knows that his body and intellect will cease to exist when he dies and are, therefore, transient and cannot realise permanent reality. He is keen to know about the prime mover of all his activities; hence his doubt which, growing larger and larger, will submerge his body, mind and environment to form a mass of fire which destroys all thoughts, feelings and passions like a re-hot stove which melts the snow that falls on it, as the masters put it. His monkey mind cannot stay in this scorching fire, and its death is automatically followed by the resurrection of his true mind which is pure and clean. This yi-qing should be maintained throughout the training until Bodhi is achieved.
After the student has wiped out all dualities in their coarse aspects, he will reach the state of bright stillness which still implies awareness of it, that is a duality of subjective ego and objective dhyana in its subtlety. They are ego and Dharma in their finest aspects mentioned in the sutras as the last hindrance on the holy path.
It is much easier to relinquish the subtle ego than the subtle Dharma which is wonderful and attractive, and can be easily mistaken for Nirvana. Hence master Han Shan says: “This is the most dangerous pass which I have myself experienced.” If the student persists in holding on to this feeling of doubt, this subtle Dharma which is but an illusion will vanish, and thus released from the last hindrance, he will leap over both phenomenon and noumenon to reach that state of Samadhi in which the ‘yi-qing’ (doubting mind) itself is sublimated and transformed into the Buddha’s all-knowledge (sarvajna). This is the Tathagata stage.
This feeling of doubt, which the masters likened to an indestructible sword, cuts down all thoughts and mental states during the training. Hence Lin Chi says: “If you meet a Buddha, cut him down; if you meet a Patriarch, cut him down; if you meet your relatives, cut them down. Only then will you be liberated, and if you are not held by externals, you will be disengaged and comfortably independent. For all visions conceived by the sense organs are unreal and can never compare to the inconceivable and inexpressible Bhutatathata.’
It is clear that the hua tou technique was not part of the original Ch’an method – which exists beyond words and phrases. Indeed, the first sutra associated with the Ch’an School in its early history is not the Surangama Sutra, but rather the Lankavatara Sutra, the influence of which waned as the literature associated with the sunyata (emptiness) thinking of the Prajnaparamitra Sutra became popular. At the time of the Song Dynasty, Dahui’s practice, therefore, was not any thing new, but rather a distinctive use of what already existed within the Ch’an School inChina. He expertly ‘turned the mind’ of those who he instructed, through the expert use of the written and spoken word. Dahui, like Xu Yun, both commented upon the dead recitation of a gong-an, with no penetrative ability to reveal the Mind Ground, as opposed to the living use of the hua tou method, which when practiced correctly, keeps an intense penetration into the mind-essence until the Mind Ground is fully revealed. The Ming Dynasty Ch’an master – Han Shan De-qing – used the hua tou method in the most efficient of manners – directly referring to the Surangama Sutra for guidance. In his autobiography, master Han Shan describes one of his experiences:
‘All the mountains were covered with snow and ice, and the scenery was just like the vision which I had had previously and which I had loved so much. My body and mind were taken by surprise as if I were entering the Paradise of Bliss. Soon after this Miao Feng left to visit Yeh Tai, and I was left alone to live in the place. I concentrated my attention on a single thought, and, if a visitor came, I did not speak but only looked at him. After a long while, when a visitor came, he resembled a tree stump. This state of mind continued until I had no idea about the meaning of a single (Chinese) character. At first a roaring gale blew frequently and when the thaw set in torrents of water rolled down the mountains and made a thunderous noise. In the stillness it was like that of a thousand marching troops and ten thousand horses galloping at full speed; it was very disturbing. Miao Feng had said: “This surrounding is created by the mind and does not come from the outside.” The ancients said: “Whoever hears the sound of water without using the sixth consciousness for thirty years, will achieve Bodhisattva Avalokitesvara’s all-pervading wisdom.” Consequently I went to a wooden bridge where I sat every day. At first the noise from the water was audible as before. After a long while it could only be heard when thoughts surged in my mind and not when they ceased to rise. Suddenly one day while sitting on the bridge as usual, I felt as if my body did not exist and the sound of the water was not heard any more. Henceforth, all the sound and noise vanished completely; I was no longer disturbed by them.’
The question of ‘who?’ is the essence of the hua tou practice, for it guides the attention of the mind away from diverse and misleading phenomena, and firmly back toward the essence of the mind itself. Of course, the questioning word ‘who?’ is a deliberate construct of the thinking mind. The word ‘who?’ becomes indicative of all words reduced to its structure – ‘W-H-O?’ – is the mind’s capacity for endless thinking and contrivance focused into a single word. The mind must first of all establish this singleness of thought through a single word – through hour upon hour of meditative practice. All words must cease except for the ‘who?’, as the developed power of concentration literally ‘pulls’ all attempts to think otherwise into its singular structure. This is the establishment of ‘singleness of thought’. Within the hua tou method, this is the achievement of ‘hua’. What gives the hua tou method its poignancy and strength is its ability to create the inner conditions whereby the ‘essence’, or ‘originator space’ of the word ‘who?’ is realised through its inherent, questioning power. The word ‘who?’ is created out of the mind’s psychic fabric through an act of concentrated ‘will’. Its structure is formed from ‘nothingness’, and it is this empty state that the ‘tou’ aspect of the hua tou method seeks to realise. Through the development of concentration, insight is attained. The mind, in its deluded state, only perceives the outer, and fully formed aspect of each thought construct, as they collectively cascade across the surface of the mind’s eye. This cascading process contains an independent energy that is not directly influenced by the mind’s eye itself. In other words, a deluded being can only helplessly watch the continuous inner dialogue, with no ability to profoundly alter its structure or course. The hua tou method allows the practitioner to take a direct control of the inner process itself, and bring a form of effective discipline to bear upon it. The endless stream of thoughts are channelled into just one stream – the question ‘who?’ – and this single stream, through an intense inner concentration is returned to its empty essence. In this regard, a hua tou may be distinguished from a gong-an by the fact that a gong-an does not necessarily have to be comprised of a question, but can be a dialogue or statement about any subject, through which the context of its utterance changes those who encounter it. A hua tou, by way of comparison, in its most developed sense, must always comprise of a question. Although both techniques perform exactly the same function of revealing the Mind Ground, a hua tou can be defined as a gong-an that is asking a specific question that can not be answered by the ordinary intellect. In a very real sense, a discussion of the history of the hua tou is allowing the ordinary mind to have a free reign in its dealings with the world, and serves as an existential contradiction to the use of the hua tou method as used by the Ch’an school, which serves to wipe out all discrimination in a single leap beyond the ‘ordinary’ and into ‘reality’. What the old Ch’an master would refer to as ‘putting a head, upon a head’. Understanding a physical history of the hua tou, although useful in an expedient manner, actually serves to obscure the very Mind Ground the hua tou method is designed to reveal. The history of the hua tou is of no use to one engaged in a serious inner quest to realise the true essence of the mind itself. This is why the Ch’an masters always advised the ‘laying down’ of the kind of clutter in the mind, such as the history of the hua tou, which is, after-all, more a matter of speculation rather than concrete fact. Intellection about the hua tou contradicts the hua tou method itself, and replaces a sound spiritual technique with a pseudo-intellectualism that mimics the logical trend of mainstream academia. Such a trend reduces the hua tou to a mere category to be filed away under the heading of ‘solved’. However, the true point of the hua tou is that it can never be solved by the intellect itself, but can only be used in the process of the transcendence of the intellect. The intellect that understands the hua tou must ultimately ‘die’ in the spiritual sense, so that a new understanding based upon wisdom can emerge out of the developmental process. The modern influence of the materialist paradigm reduces the spiritual to the realm of matter, where it can be measured and quantified. This is the dismantling of Ch’an Buddhism from within, and its destructive influence should be noted by those who believe that a spiritual method should be maintained in a format that allows it to be used effectively in creating better human beings, through the realisation of enlightenment itself. A hua tou that can be measured and understood by the ordinary mind, is a hua tou that is spiritually useless. Intellectual understanding should not replace spiritual transcendence.
Whereas the Surangama Sutra turns the attention inward, and follows the hearing of sound back to its original essence, the developed Chinese method of the use of hua tou aids the ‘inward looking’ by adding the introspective power of the enquiring ‘who?’ to its functioning. Although it is possible for beings with good spiritual karma to follow sound back to its essence, generally speaking ordinary beings find this practice difficult. This is why the Surangama method was modified into the hua tou. The hua tou assists the mind to turn inward and away from external stimuli. When simply ‘looking’ at sound as it arises, the clutter of the mind can get in the way of the observational process. The hua tou remedies this situation by gathering-up all the clutter into one singe, questioning word – ‘who?’ Beings of high spirituality have little or no mind clutter and are therefore able to penetrate straight through to the Mind Ground by following the sound back to its empty root, using only the Surangama method. However, the method itself, be it the hua tou, or the Surangama, is not the achievement and should not be confused with it. The enlightened Ch’an masters often spoke against resting in the extreme of ‘attainment’, or ‘non-attainment’. Peter Hershock explains:
‘Huineng urged his monastic and lay students to take the “precepts of formlessness” and to practice the “formless repentance,” insisting that Chan did not have to do with any particular bodily posture or mental state but with having a complete confidence in one’s own true nature and demonstrating one’s capacity for conduct without precedent. Linji himself admitted that his approach to Chan left many people clucking their tongues and thinking him a simpleton or a fool. Apparently, the distinctive character of Chan practice does not rest on any norms or standards of bodily comportment.
But neither does it rest on the achievement of some “internal” state of affairs, the attainment of particular, subjective experienced altered states and supernatural powers, or the realisation of intellectual or rhetorical brilliance. Mazu is adamant that “talk about attainment is your mind. Talk about nonattainment is still your mind. Even if you were to get as far as splitting the body, emanating light, and manifesting the eighteen subtle transformation…[or] if you were able to talk about the Buddha’s expedient teachings for as many eons as there are grains of sand in a river, you’ll still never complete your explanation or get anywhere. All these are just like not-yet-severed barbs and chains.” For Mazu, and for Chan generally, entering into meditative absorption or stillness and demonstrating scholarly brilliance are equally classed as overdoing it.’
Master Xu Yun explained that correct knowledge of the ‘Way’ (Dao) is required for access to the Ch’an path. However, once the gate of Ch’an has been successfully entered, any and all excess baggage must be abandoned completely, and this includes any attempt to define the path itself into materially concrete terms. Even the great Ch’an master Dahui agreed with this possession when he wrote to Huang Po-ch’eng:
‘In the daily activities of a student of the Path, to empty objects is easy, but to empty mind is hard. If objects are empty but mind is not empty, mind will be overcome by objects. Just empty the mind, and objects will be empty of themselves. If the mind is already emptied, but then you arouse a second thought, wishing to empty its objects, this means that this mind is not yet empty, and is again carried away by objects. If this sickness is not done away with, there is no way to get out of birth and death. Haven’t you seen the verse which Layman Pang presented to Ma Tsu?
“In the ten directions, the same congregation:
Each and every one studies non-doing.
This is the place where Buddhas are chosen:
Minds empty, they return successful.”
Once the mind is empty, then what is there outside of mind that can be emptied? Think it over.’
 Luk, Charles. The Surangama Sutra (Leng Yen Ching) (2001) Munishram Manoharlal – the Title page reads; ‘Chinese Rendering by Master Paramiti of Central North India at Chih Chih Monastery,AD 705.’
 Luk, Charles. The Secrets of Chinese Meditation (1984) Weiser – Pages 32-42 – which quotes the Surangama Sutra. SSee also:
Luk, Charles. The Surangama Sutra (Leng Yen Ching) – Pages 135-142 – for Avalokitesvara’s full explanation of this method.
 Cleary, JC. Swampland Flowers: The Letters and Lectures of Zen Master Ta Hui (1977) Shambhala.
 Schlutter,Morten. How Zen Became Zen, (2009) Munishram Manoharlol – Page 107.
 Schlutter,Morten. How Zen Became Zen, (2009) Munishram Manoharlol. – 215.
 Cleary, JC. Swampland Flowers: The Letters and Lectures of Zen Master Ta Hui (1977) Shambhala – Pages 84-85. When reading through the letters in this collection, none appear to provide instruction that resemble the developed hua tou, even though Dahui is obviously enlightened and correctly turning the mind’s of others back upon the empty essence. Dahui’s brilliance is not limited to the expedient of the hua tou technique.
 Lachs, Stuart. Hua-t’ou: A Method of Zen Meditation – http://www.thezensite.com/ZenTeachings/HuaTou_Lachs.pdf Accessed 11.4.2012 – The opening paragraph reads: ‘This paper discusses a form of meditation practice known in Chinese as hua- t’ou. It was popularized by the Chinese Zen master Ta-Hui (1089 – 1163) a member of the Lin-Chi sect of Zen. While Ta-Hui did not invent this method of meditation, he popularized it in that he was the first to teach a theory of why hua`t’ou should be practiced, and also taught how to use it in Zen practice.’
 Luk, Charles. ‘Empty Cloud The Autobiography of a Chinese Zen Master’ (1988) Element – Page 158.
公案(gong-an): 公 (gong1) is written as an open mouth that shares speech in a public setting and in this context is used to mean ‘public’. 案 (an4) refers to the presentation of a legal document or record, upon a long table, in this context it carries the meaning of ‘record’. Therefore, 公案 (gong-an) refers to a ‘public record’, or recorded dialogue between master and student within the Ch’an tradition.
 Luk, Charles. ‘Empty Cloud The Autobiography of a Chinese Zen Master’ (1988) Element – Page 158.
 Luk, Charles, ‘Practical Buddhism’ (1988) Rider & Co – pages 22-24. For sake of clarity, I have substituted the Wades-Giles ‘i-ch’ing’ for the modern pinyin of ‘yi-qing’, so as to differentiate between the concept expressed here of a ‘doubting mind’, and the well known Book of Changes, otherwise known as the I Ching [Yijing], etc. Readers should be aware that although Luk talks of a ‘feeling of doubt’ (yi-qing), in the Chinese texts the expression is usually ‘da-yi-qing’ (大疑情), or ‘great doubting mind’). Shi Da Dao – author.
 Luk, Charles. Practical Buddhism (1988), Rider & Co Ltd – Pages 80-81.
 Hershock, Peter. Chan Buddhism, (2004)Hawai’i Press – Pages 133-134.
 Cleary, JC. Swampland Flowers: The Letters and Lectures of Zen Master Ta Hui (1977) Shambhala – Pages 31-32.