lets look at some of the infomation on viññāṇadhātu and manoviññāṇadhātū
From Vis. XV
517.Tadanantarā pana dhātuyoti aṭṭhārasa dhātuyo – cakkhudhātu, rūpadhātu, cakkhuviññāṇadhātu, sotadhātu, saddadhātu, sotaviññāṇadhātu, ghānadhātu, gandhadhātu, ghānaviññāṇadhātu, jivhādhātu, rasadhātu, jivhāviññāṇadhātu, kāyadhātu, phoṭṭhabbadhātu, kāyaviññāṇadhātu, manodhātu, dhammadhātu, manoviññāṇadhātūti.
17.The “elements” next to that (XIV.32) are the eighteen elements, that is to say, eye element, visible-data element, eye-consciousness element; ear element, sound element, ear-consciousness element; nose element, odour element, nose- consciousness element; tongue element, flavour element, tongue-consciousness element; body element, tangible-data element, body-consciousness element; mind element, mental-data element, mind-consciousness element.
Tasmā yathāvuttena atthena cakkhu ca taṃ dhātu ca cakkhudhātu - pe - manoviññāṇañca taṃ dhātu ca manoviññāṇadhātūti.
22. it is an eye and that is an element, thus it is the eye-element … It is mind- consciousness and that is an element, thus it is mind-consciousness element.
so why did the Buddha (and sariputta ) give such profound teachings?
521Santi hi sattā vijānanasabhāve viññāṇe jīvasaññino, tesaṃ cakkhusotaghānajivhākāyamanodhātumanoviññāṇadhātubhedena tassa anekataṃ cakkhurūpādipaccayāyattavuttitāya aniccatañca pakāsetvā dīgharattānusayitaṃ jīvasaññaṃ samūhanitukāmena bhagavatā aṭṭhārasa dhātuyo pakāsitā.
for there are beings who perceive a soul in consciousness, the individual essence of which is cognizing.
And so the Blessed One, who was desirous of eliminating the long-inherent perception of a soul, has expounded the eighteen elements thus making evident to them not only consciousness’s multiplicity when classed as eye-, ear-, nose-, tongue- and body-consciousness elements, and mind, and mind-consciousness elements, but also its impermanence, which is due to its existing in dependence on eye- cum-visible-data, etc., as conditions
.
here the Vis defines the terms +
522 Manodhātu pana pañcadvārāvajjanakusalākusalavipākasampaṭicchanavasena tayo dhammāti saṅkhaṃ gacchati. The mind element is reckoned as three things, namely, five-door adverting (70), and profitable (39) and unprofitable (55) resultant receiving.
Dhammadhātu tiṇṇaṃ arūpakkhandhānaṃ soḷasannaṃ sukhumarūpānaṃ asaṅkhatāya ca dhātuyā vasena vīsati dhammāti saṅkhaṃ gacchati.
XV 34The mental-data element as twenty things, namely, three immaterial aggregates, sixteen kinds of subtle matter, and the unformed element (see Vibh 88).15 : 15. In XIV.35–70, the material instances listed total 28, that is, 4 primary elements, 9 sense faculties (excluding the tangible-data facult…
Manoviññāṇadhātu sesakusalākusalābyākataviññāṇavasena chasattati dhammāti saṅkhaṃ gacchati.
Mind-consciousness element is reckoned as seventy-six things, namely, the remaining profitable, unprofitable, and indeterminate consciousnesses.
añcannaṃ pana nesaṃ āvajjanamanodhātu anantarasamanantaranatthivigatānantarūpanissayavasena pañcahi paccayehi paccayo hoti, tā ca pañcapi sampaṭicchanamanodhātuyā.
36. The adverting mind element (70) is a condition, as the five conditions, namely: proximity, contiguity, absence, disappearance, and proximity-decisive- support, for these five [beginning with the eye-consciousness element]. And these five are so too for the receiving mind element ((39), (55)).
Tathā sampaṭicchanamanodhātu santīraṇamanoviññāṇadhātuyā, sā ca voṭṭhabbanamanoviññāṇadhātuyā, voṭṭhabbanamanoviññāṇadhātu ca javanamanoviññāṇadhātuyā. And so is the receiving mind element for the investigating mind-consciousness element ((40), (41), (56)). And so is that too for the determining mind-consciousness element (71). And so is the determining mind-consciousness element for impulsion mind- consciousness element.
Javanamanoviññāṇadhātu pana anantarāya javanamanoviññāṇadhātuyā tehi ceva pañcahi āsevanapaccayena cāti chahi paccayehi paccayo hoti.
But the impulsion mind-consciousness element is a condition, as the six conditions, namely, as the five already stated and as repetition condition, for the immediately following impulsion mind-consciousness element.
Esa tāva pañcadvāre nayo.
This, firstly, is the way in the case of the five doors.
Manodvāre pana bhavaṅgamanoviññāṇadhātu āvajjanamanoviññāṇadhātuyā.
37. In the case of the mind door, however, the life-continuum mind- consciousness element is a condition, for the adverting mind-consciousness element (71)
Āvajjanamanoviññāṇadhātu ca javanamanoviññāṇadhātuyā purimehi pañcahi paccayehi paccayo hoti.
as the previously-stated five conditions. And the adverting mind- consciousness element is so for the impulsion mind-consciousness element.
Dhammadhātu pana sattannampi viññāṇadhātūnaṃ sahajātaaññamaññanissayasampayuttaatthiavigatādīhi bahudhā paccayo hoti.
38. The mental-data element is a condition in many ways, as conascence, mutuality, support, association, presence, non-disappearance, etc.,16 for the seven consciousness elements.
Cakkhudhātuādayo pana ekaccā ca dhammadhātu ekaccāya manoviññāṇadhātuyā ārammaṇapaccayādīhipi paccayā honti.
The eye element, etc., and some of the mental-data element,17 are conditions, as object condition, etc., for some of the mind- consciousness element.
For me it is a sign of the omniscience of the Buddha that he could define these elements. It is so useful to learn to see this as: imagine for how many lives we have, from birth to death, taken for granted that I see, it is my mind that is seeing , hearing, thinking. All the while completely ignorant of that it is only momentary elements performing their function.