I. The Dhammasangani Pali
The Dhammasangani, the first book of the Abhidhamma, and the Patthana, the last book, are the most important of the seven treatises of Abhidhamma, providing as they do the quintessence of the entire Abhidhamma.
Scheme of Classification in the Dhammasangani(1) The Matika
The Dhammasangani enumerates all the dhammas (phenomena) i.e., all categories of nama, namely, Consciousness and mental concomitant, and , rupa, Corporeality. Having enumerated the phenomena, they are arranged under different heads to bring out their exact nature, function and mutual relationship both internally (in our own being) and with the outside world. The Dhammasangani begins with a complete list of heads called the Matika. The Matika serves as a classified table of mental constituents treated not only in the Dhammasangani but in the entire system of the Abhidhamma.
The Matika consists altogether of one hundred and twenty two groups, of which the first twenty two are called the Tikas or Triads, those that are divided under three heads; and the remaining one hundred are called the Dukas or Dyads, those that are divided under two heads.
Examples of Triads are:
(a) Kusala Tika: dhammas
(i) that are moral, kusala,
(ii) that are immoral, akusala,
(iii) that are inderterminate, abyakata.
(b) Vedana Tika: dhammas that are associated
(i) with pleasant feeling,
(ii) with painful feeling,
(iii) with neutral feeling.
Examples of Dyads are:
(a) Hetu Duka: dhammas
(i) that are roots, hetus
(ii) that are not roots, ne-hetu.
(b) Sahetuka Duka: dhammas
(i) that are associated with the hetus
(ii) that are not associated with the hetus.
The Matika concludes with a list of the categories of dhamma entitled Suttantika Matika made up of' forty two groups of dhamma found in the suttas. (2) The four Divisions
Based on these Matikas of Tikas and Dukas, the Dhammasangani is divided into four Divisions:
(i) Cittuppada Kanda. Division on the arising of consciousness and mental concomitants.
(ii) Rupa Kanda, Division concerning corporeality.
(iii) Nikkhepa Kanda, Division that avoids elaboration.
(iv) Atthakatha Kanda, Division of Supplementary Digest
Of the four divisions, the first two, namely, Cittuppada Kanda and Rupa Kanda form the main and the essential portion of' the book. They set the model of thorough investigation into the nature, properties, function and interrelationship of each of the dhammas listed in the Matika, by providing a simple analysis and review of the first Tika, namely, the Kusala Tika of Kusala, Akusala and Abyakata Dhamma. Cittuppada Kanda deals with a complete enumeration of all the states of mind that come under the headings of Kusala and Akusala; the Rupa Kanda is concerned with all states of matter that come under the heading of Abyakata; mention is also made of Asankhata Dhatu (Nibbana) without discussing it.
The Nikkhepa Kanda, the third division, gives, not too elaborately nor too briefly, the summary of distribution of all the Tikas and Dukas, so that their full contents and significance will become comprehensible and fully covered.
Atthakatha Kanda, the last division of the book, is of the same nature as the third division, giving a summary of the dhammas under the different heads of the Tika and the Duka groups. But it provides it in a more condensed manner, thus forming a supplementary digest of the first book of the Abhidhamma for easy memorizing. (3) Order and classification of the types of Consciousness as discussed in Cittuppada Kanda.
The Cittuppada Kanda first gives a statement of the types of Consciousness arranged under the three heads of the first Tika, namely, (i) Kusala Dhamma i.e., Meritorious Consciousness and its concomitants (ii) Akusala Dhamma i.e., Demeritorious Consciousness and its concomitants (iii) Abyakata Dhamma i.e., Indeterminate Consciousness and its concomitants. The list of mental concomitants for each dhamma is fairly long and repetitive.
The statement of the types of Consciousness is followed by identification of the particular type, e.g. Kusala Dhamma, in the form of question and answer, with regard to the plane or sphere (bhumi) of Consciousness: Kamavacara, sensuous plane; Rupavacara, plane of form; Arupavacara, plane of no-form; Tebhumaka, pertaining to all the three planes; or Lokuttara, supramundane, not pertaining to the three planes.
The type of Consciousness for each plane is further divided into various kinds e.g., there are eight kinds of Kusala Dhamma for the sensuous plane: first Kusala Citta, second Kusala Citta etc.; twelve kinds of Akusala Citta; eight kinds of Ahetuka Kusala Vipaka Citta and eight kinds of Sahetuka Vipaka Citta under the heading of Abyakata Dhamma.
Then these various kinds are further analysed according to:
(i) Dhamma Vavatthana Vara e.g., the particular quality, whether accompanied by joy etc. i.e., somanassa, domannassa, sukha, dukkha or upekkha.
(ii) Kotthgsa Vara, the grouping of dhammas. There are twenty three categories of dhammas which result from synthetical grouping of dhammas into separate categories such as khandhas, ayatanas, dhatus etc.
(iii) Sunnata Vara, which lays stress on the fact that there is no 'self' (atta) or jiva behind all these dhammas; they are only composites, causally formed. and conditioned, devoid of any abiding substance.
The same method of treatment is adopted for the akusala and abyakata types of Consciousness.(4) Rupa Kanda
Because Dhammasangani treats all the dhammas (namas as well as rupas) in the same uniform system of classification, Rupa Kanda is only a continuation of the distribution of the Dhamma under the heads of the first Tiks which begins in the first division, Cittuppada Kanda. In the Cittuppada Kanda, the enumeration of the Dhamma under the head 'Abyakata' has been only partially done, because abyakata type of Dhamma includes not only all the states of mind which are neither meritorious nor demeritorious but also all states of matter and the Asankhata Dhatu or Nibbana. The portion of Dhamma under the heading of Abyakata, which has been left out from cittuppada Kanda is attended to in this Kanda.
The method of-treatment here is similar, with the difference that instead of mental concomitants, the constituents of matter, namely, the four primary elements and the material qualities derived from them with their properties and their relationships are analysed and classified.