The Abhidhamma Pitaka

It deals with the philosophy and psychology of the Theravada school of Buddhism. The Theravada, however, refers to that school of Buddhism which, supposedly adhere to the most original and purest form of the Buddhist teachings, advocated by those theras (monks) who obtained the erudition directly through the Master. Further, they used the bhasa Magadhika or the mula bhasa (the original language) [1] to record the original text or the pariyaya, (the text of the canons). The term pariyaya, however, when abbreviated became pari or Pali; and in course of time was applied to denote the language of the entire gamut of the canons; and the exegeses and other compositions on those texts having the same language.

Aggam bahusuttadinam, kosarakkham mahesino

Sammannitvana attanam thero dhammam apucchi so

Tatha sammanniyattanam dhammasanagato sayam

Visajjesi tam Ananda-thero dhamm asesato. (Mahavamsa 34-35)

The other two Pitakas or the collection of the Buddhist canons are the Vinaya Pitaka (Collection of the codes and conducts for the monks and nuns) and Sutta Pitaka (the collection of the discourses of the Buddha).