Buddhaghosa was not an independent thinker but he makes amends for his want of originality not only by his industry and learning but by his power of grasping and expounding the whole of an intricate subject. His Visuddhi-magga has not yet been edited in Europe, but the extracts and copious analysis[80] which have been published indicate that it is a comprehensive restatement of Buddhist doctrine made with as free a hand as orthodoxy permitted. The Mahâvamsa observes that the Theras held his works in the same estimation as the Piṭakas. They are in no way coloured by the Mahayanist tenets which were already prevalent in India, but state in its severest form the Hinayanist creed, of which he is the most authoritative exponent. The Visuddhi-magga is divided into three parts treating of conduct (sîlam), meditation (samâdhi) and knowledge (paññâ), the first being the necessary substratum for the religious life of which the others are the two principal branches. But though he intersperses his exposition with miraculous stories and treats exhaustively of superhuman powers, no trace of the worship of Mahayanist Bodhisattvas is found in his works and, as for literature, he himself is the chief authority for the genuineness and completeness of the Pali Canon as we know it. When we find it said that his works were esteemed as highly as the Piṭakas, or that the documents which he translated into Pali were the words of the Buddha[81], the suspicion naturally arises that the Pali Canon may be in part his composition and it may be well to review briefly its history in Ceylon. Our knowledge appears to be derived entirely from the traditions of the Mahâvihâra which represent Mahinda as teaching the text of the Piṭakas orally, accompanied by a commentary. If we admit the general truth of the narrative concerning Mahinda's mission, there is nothing improbable in these statements, for it would be natural that an Indian teacher should know by heart his sacred texts and the commentaries on them. We cannot of course assume that the Piṭakas of Mahinda were the Pali Canon as we know it, but the inscriptions of Asoka refer to passages which can be found in that canon and therefore parts of it at any rate must have been accepted as scripture in the third century B.C. But it is probable that considerable variation was permitted in the text, although the sense and a certain terminology were carefully guarded. It was not till the reign of Vaṭṭagâmaṇi, probably about 20 B.C., that the canon was committed to writing and the Parivâra, composed in Ceylon[82], was included in it.