Patthana

The Patthana, the Book of Conditional Relations, is by most reckonings the longest single text in the entire Pali Canon, running in some standard printed editions to many thousands of pages, and it stands as the Abhidhamma Pitaka's culminating achievement, taking the phenomena the Dhammasangani had painstakingly enumerated and systematically working through twenty four distinct modes of conditionality, paccaya, by which any given phenomenon can causally relate to and support the arising of another, root condition, object condition, proximity condition, and twenty one others, each precisely defined and then applied across the full range of possible combinations of mental and physical phenomena the earlier Abhidhamma books had classified.

Where the Dhammasangani offers something like a static inventory of every possible type of experience, the Patthana supplies the dynamic, causal grammar explaining how those experiences actually arise, condition and give way to one another moment by moment, providing what the Theravada tradition regards as the fullest possible account of dependent origination worked out at the most granular level of analysis the Abhidhamma method is capable of. Its sheer combinatorial scope, applying twenty four conditions across the entire matika of categories established in the first book, accounts for its extraordinary length relative to every other text in the canon.

Theravada tradition holds the Patthana in a position of unmatched reverence among all the texts of the Tipitaka, teaching that the Buddha spent the fourth of the seven weeks following his enlightenment contemplating precisely this system of conditional relations, and that his mind's comprehension of its vast, intricate causal web became so complete and luminous that six colored rays are said to have radiated from his body during this contemplation, an image that later became the source of the six colors used in the modern Buddhist flag, first designed in Sri Lanka in the 19th century and now flown by Buddhist communities of every tradition worldwide. This traditional veneration reflects a real doctrinal judgment within Theravada thought: because the teaching of dependent origination, that all phenomena arise through conditions rather than through an uncaused or independently existing self, sits at the very center of the Buddha's awakening, the Patthana's exhaustive working out of exactly how that conditioning operates is understood as the fullest possible unpacking of the insight the entire teaching rests on.

Modern scholars, while not sharing the tradition's devotional framing, generally agree the Patthana represents the most sophisticated and philosophically ambitious achievement of the entire Abhidhamma project, a systematic attempt, without clear parallel elsewhere in the ancient world's surviving religious literature, to specify with exhaustive precision every mode by which conditioned reality actually operates.