of the person, or temporal eternalism). Thus, according to Frauwallner, the different Abhidharma canons contained collections of doctrines which were sometimes unrelated to each other and sometimes contradictory. These various Abhidhammic theories were (together with differences in Vinaya) some of the various causes for the splits in the monastic Sangha, which resulted in the fragmented early Buddhist landscape of the Early Buddhist schools. However, these differences did not mean the existence of totally independent sects, as noted by Rupert Gethin, "at least some of the schools mentioned by later Buddhist tradition are likely to have been informal schools of thought in the manner of ‘Cartesians,’ ‘British Empiricists,’ or ‘Kantians’ for the history of modern philosophy." By the 7th-century, Chinese pilgrim Xuanzang could reportedly collect Abhidharma texts from seven different traditions. These various Abhidharma works were not accepted by all Indian Buddhist schools as canonical, for example, the Mahasanghika school seems not to have accepted them as part of the canon. Another school included most of the Khuddaka Nikaya within the Abhidhamma Pitaka. After the closing of the various Buddhist canons, Abhidharma texts continued to be composed, but now they were either commentaries on the canonical texts (like the Pali Aṭṭhakathās and the Mahāvibhāṣa), or independent treatises ('śāstra') in their own right. In these post-canonical texts, further doctrinal developments and innovations can be found. As Noa Ronkin writes, "post-canonical Abhidharma texts became complex philosophical treatises employing sophisticated methods of argumentation and independent investigations that resulted in doctrinal conclusions quite far removed from their canonical antecedents." As Frauwallner writes, these later works were attempts to build truly complete philosophical systems out of the various canonical Abhidharma texts. Some of these texts surpassed the canonical Abhidharma in influence and popularity, becoming the orthodox summas of their particular schools' Abhidharma. Two exegetical texts, both from the 5th century, stand above the rest as the most influential. The work of Buddhaghosa (5th century CE), particularly the Visuddhimagga, remains the main reference work of the Theravāda school, while the Abhidharmakośa (4-5th century CE) of Vasubandhu remains the primary source for Abhidharma studies in both Indo-Tibetan Buddhism and East Asian Buddhism. In the modern era, only the Abhidharmas of the Sarvāstivādins and the Theravādins have survived as complete collections, each consisting of seven books with accompanying commentarial literature. A small number of other Abhidharma texts are preserved in the Chinese canon and also in Sanskrit fragments, such