The Pāli Abhidhamma was not recognized outside the Theravāda school. The Tipitaka is composed of 45 volumes in the Thai edition, 40 in the Burmese and 58 in the Sinhala, and a full set of the Tipitaka is usually kept in its own (medium-sized) cupboard. According to Kate Crosby:Since much Sutta material overlaps with that found in the Sūtra collections of other Buddhist traditions, it is the Vinaya (monastic discipline) and Abhidhamma that are the most distinctive formal aspects of Theravāda Buddhism, unique to Theravāda.The Vibhajjavāda school (‘the analysts’), the branch of the Sthāvira school from which Theravāda is derived, differed from other early Buddhist schools on a variety of teachings. The differences resulted from the systematization of the Buddhist teachings, which was preserved in the Abhidharmas of the various schools. The unique doctrinal positions of the Theravāda school are expounded in what is known as the Abhidhamma-piṭaka, as well as in the later Pāli commentaries ("Aṭṭha-kathā") and sub-commentaries ("ṭīkā"). Because of the size of this canonical and commentarial literature the Pāli tradition developed a tradition of handbooks and doctrinal summaries, the most influential of which are the "Visuddhimagga" and the "Abhidhammaṭṭhasaṅgaha." The Pāli Abhidhamma is "a restatement of the doctrine of the Buddha in strictly formalized language ... assumed to constitute a consistent system of philosophy". Its aim is not the empirical verification of Buddhist teachings, but "to set forth the correct interpretation of the Buddha's statements in the "Sutra" to restate his 'system' with perfect accuracy". Because Abhidhamma focuses on analyzing the internal lived experience of beings and the intentional structure of consciousness, the system has often been compared to a kind of phenomenological psychology by numerous scholars such as Nyanaponika, Bhikkhu Bodhi and Alexander Piatigorsky. The Theravāda school has traditionally held the doctrinal position that the canonical Abhidhamma Pitaka was actually taught by the Buddha himself. Modern scholarship in contrast, has generally held that the Abhidhamma texts date from the 3rd century BCE.