[Image] Mahākātyāna
Stele, Korea. This text is "hidden" because even though it has been translated into English (Choong 2010), it has not been discussed in relation to the other versions of the text so far as I'm aware. What tends to happen is that when the text is mentioned, scholars think of the Pāli version or the Sanskrit passage cited by Candrakīrti in his commentary on Nāgārjuna's Mūlamadhyamaka Kārikā which mentions the Kātyāyana Sūtra (MMK 15.7). I'm hoping to give some prominence to the other versions of which two are in Chinese.

The Pali Kaccānagotta Sutta (SN 12.15 = KP) is quoted verbatim in the Channa Sutta (SN 22.90; iii.132-5) and as such is of little interest except that when a text is cited by another text we get a sense of relative dating: it implies chronology. In the Chinese Saṃyuktāgama, the counterpart of the Channa Sutta (CC; SĀ 262 = T 2.99 66c01-c18) also quotes the Chinese counterpart of the Kātyāyana Sūtra (KC; SĀ 301), but in this case the text is different in some interesting ways. And thus we have a fourth version of the text: KP, KS, KC and now CC.
Most significant is how the two Chinese versions deal with a partic-ularly difficult paragraph that in Pali and Sanskrit reads: KP: dvayanissito khvāyaṃ kaccāna loko yebhuyyena atthitañceva natthitañca. Upayupādānābhinivesavinibandho khvāyaṃ, kaccāna, loko yebhuyyena. Tañcāyaṃ upayupādānaṃ cetaso adhiṭṭhānaṃ abhinivesānusayaṃ na upeti na upādiyati nādhiṭṭhāti ‘attā me’ti. “Generally, Kaccāna, this world relies on a dichotomy: existence and non-existence.” Usually, Kaccāna, this world is bound to the tendency to grasping and attachment. And he does not attach, does not grasp, is not based on that biased, obstinate tendency of the mind to attachment and grasping: [i.e.] “[this is] my essence”.  ~~~ KS: dvayaṃ niśrito ’yaṃ kātyāyana loko yadbhūyasāstitāñ ca niśrito nāstitāñ ca | Upadhyupādānavinibaddho ’yaṃ kātyāyana loko yad utāstitāñ ca niśrito nāstitāñ ca | etāni ced upadhyupādānāni cetaso ’dhiṣṭhānābhiniveśānuśayān nopaiti nopādatte nādhitiṣṭhati nābhiniviśaty ātmā meti | “Generally, Kātyāyana, this world relies on a dichotomy: it relies on existence and non-existence. This world, which relies on existence and non-existence, is bound by attachments and grasping. If he does not attach to these, does not grasp, is not based on or devoted to the biased, obstinate tendency of the mind to attachments and grasping: “[this is] my essence”. ~~~
Notes

The syntax here is tortuous and in addition contains some distracting word play. The nouns in the green section are from the same roots as the verbs in the orange section. Both Chinese versions replicate this same structure. It's possible that the nouns and verbs are meant to be understood as linked: upāyaṃ with na upeti; upādānaṃ with na upādiyati and so on, but at this stage I'm unsure. The Sanskrit is more difficult to parse because of the "if" (ced) and the Pali seems like a better reading for not having it. 
Note that P "attā me" & Skt "ātmā me" appear to be references to the formula often used with reference to the skandhas. Here wrong view would be of the form: rūpaṃ etam mama, eso’ham amsi, eso me attā ti samanupassati.
He considers form: “it is mine”; “I am this”; “this is my essence”. Our text hints that the duality of existence (astitā) and non-existence (nāstitā) arises from the same wrong view. Indeed seeing experience in terms of existence and non-existence is probably at the heart of interpreting it as "mine", "I" or "my essence". 
The Saṃyuktāgama text translated into Chinese was evidently similar to the Sanskrit of KS and carried out by Guṇabhadra in the 5th century CE. Even non-Chinese-readers will see there are similarities and differences in the two Chinese versions of this paragraph, which I've marked up using the same colour scheme as above for comparison. KC: “世間有二種依， 若有、 若無，為取所觸； 取所觸故，或依有、或依無。若無此取者。心境繫著。使不取、不住、不計我。 KC: “Among the worldly (世間) two categories are relied on: being and non-[being]. Because of having grasping the touched, they either rely on being or non-being. If he is not a seizer of that , he doesn’t have the obstinate mental state of attachment; he doesn’t insist on, or think wrongly about ‘I’.” ~~~ CC: 『世人顛倒依於二邊，若有、若無，世人取諸境界，心便計著。迦旃延！若不受、不取、不住、不計於我， CC: “Wordly people (世人) who are topsy-turvy (顛倒) rely on (依) two extremes (二邊): existence (若有) and non-existence (若無). Worldly people (世人) generally (諸) adhere to (取) perceptual objects (境界) [because of]  because of biased, obstinate tendency of the mind (心便計著) Kātyāyana: if not appropriating (受), not obtaining (取), not abiding (住), not attached to or relying on ‘I’...” ~~~
The first difference is in interpreting Skt/P. loka. KC translates 世間 while CC has 世人: "in the world" versus "worldly people". CC adds that the worldly people are 顛倒 "top-down" or "upside-down" or "topsy-turvy". Choong translates "confused", which is perfectly good, but there's a connotation in Buddhist jargon of viparyāsa (c.f. DDB sv 顛倒) which refers to mistaking the impermanent for the permanent and so on.
KC and CC both translate niśrito/nissito as 依. But they again differ in how they convey dvayam: KC 二種 "two varieties" and CC 二邊 "two sides". The character 邊 often translates Skt. anta which is significant because the word crops up later in the text in the Sanskrit and Pali: Skt: ity etāv ubhāv antāv anupagamya madhyamayā pratipadā tathāgato dharmaṃ deśayati | Thus, the Tathāgata teaches the Dharma by a middle path avoiding both these extremes. KC and CC both use 二邊 in this latter passage. It makes more sense to refer to "two extremes" (antau; in the dual) early on if that's what's talked about later, especially when by "later" we mean just three sentences later. Thus CC provides better continuity than KC.
The next part of this section is where the two texts differ most markedly.
KC: Because of having grasping the touched (取所觸), they either rely on being or rely on non-being (或依有、或依無). If [he is] not a seizer of that (若無此取者), he doesn't have the obstinate mental state of attachment (心境繫著).

CC: worldly people generally (境 ) adhere and attach to 計著 objects of the mind (界心). Kātyāyana: if not appropriating (受), not obtaining (取), not abiding (住), not attached to or relying on “I”...

(Choong "Worldlings become attached to all spheres, setting store by and grasping with the mind.") In KC we have some confusion around the phrase 取所觸. In Choong's translation of KC (40) he wants to have it mean “This grasping and adhering" but that's not what it appears to say and in any case no dictionary I have access to translates 觸 chù as ‘adhere’ or anything like it. On face value, and taking into account Buddhist Chinese it says "grasping what is touched": 取 = Skt. upādāna; 所 = relative pronoun; 觸 = Skt. sparśa < √spṛś 'touch'. In other words Guṇabhadra seems to have made a mistake here. I think Choong is tacitly amending the text to correct it, probably based on reading the Pali.

Elsewhere KS seems to be defective: KP has upay(a)-upādāna-abhinivesa-vinibandha ‘bound by the tendency to attachment and grasping’ whereas KS has upadhy-upādāna-vinibaddho, missing out abhinivesa, which doesn't really make sense. Upadhi is out of place here and probably a mistake for upāya. It may be that the source text for KC was also defective. 
Note that CC has abbreviated the text. The green section of KC repeats some of the first red section, but CC eliminates the repetition and makes the paragraph easier to read overall. 
The Chinese texts both run on to include the next section, although it's clear from KP and KS that the next part is a separate sentence. 

Conclusion

"In short, when reading any given line of a Chinese Buddhist sūtra—excepting perhaps those produced by someone like Hsüan-tsang, who is justifiably famous for his accuracy—we have a roughly equal chance of encountering an accurate reflection of the underlying Indian original or a catastrophic misunderstanding." Jan Nattier. A Few Good Men. p.71
As a warning this might be slightly overstated for effect and it is qualified by Nattier who says that multiple translations make it easier for the scholar. But it's often true that in order to really get what a Chinese text is on about, one must use the Indic (Pāḷi, Saṃskṛta, Gāndhārī) text as a commentary. This is partly because Buddhist Chinese is full of transliterations and jargon. Words are used in ways that are specific to a Buddhist context and must be read as technical terms. Buddhist Chinese very often uses something approximating Sanskrit syntax (Chinese is an SVO language while Sanskrit is SOV). The paragraph we have been considering is a good example of this phenomena as the Chinese apes the syntax of the Sanskrit. 
It's hard to avoid the conclusion that KC and CC were translated by different people and that the translator of CC did a slightly better job than the translator of KC. So perhaps the named translator, Guṇabhadra, was a sort of editor-in-chief working with a team? This was a common way of creating Chinese translations. Or perhaps he translated the same passage twice and did it differently each time? Though this seems less likely. 
By comparison with the Pāli Tipiṭaka we expect KC and CC to be identical, as the quotation of KP in the Channa Sutta is verbatim. The fact that they are not raises questions about the source text for the Samyuktāgama translated in Chinese. Having different translations into Chinese is valuable because it is precisely where KC is difficult that CC is different and arguably clearer. But perhaps the different translations are because the source text itself was different? KS is different from KP in other ways, and different from citations in later literature. This points to a number of versions of the text being in circulation of which we have a sample in the various canons.

So often the Chinese Tripiṭaka contains little that conflicts with the Pāḷi Tipiṭaka. But sometimes, as in this case, the differences are instructive, especially where versions in Sanskrit and/or Gāndhārī survive. We're now starting to see the treatment of Pali and Chinese versions of texts side by side in articles about early Buddhism. No doubt the publication of canonical translations into English, which has begun, will facilitate this. Certainly Early Buddhism is no longer synonymous with Theravāda and Pāḷi.

My close reading of all four Kātyāyana texts is slowly becoming a journal article. A subsequent project will be to explore the many citations of the text in Mahāyāna Sūtras. Exact citations or mentions of the same idea can be found in at least the Aṣṭasāhasrikā Prajñāpāramitā Sūtra  and the Laṅkāvatāra Sūtra, and also in Nāgarjuna's Mūlamadhyamakakārikā and especially in Chandrakīrti's commentary on MMK, Prasannapāda. Thus the text and the ideas in it were foundational to the Mahāyāna and provide an important thread of continuity, between the first two great phases of Buddhist thought.

~~oOo~~