This work being completed, extraordinary precautions soon began to be taken to guard the canonical text thus fixed against the possibility of any change or loss. The result has been its preservation with a faithfulness unique in literary history. The first step taken in this direction was the constitution of the Pada, or "word" text, which being an analysis of the Samhita, gives each separate word in its independent form, and thus to a considerable extent restores the Samhita text to an older stage. That the Pada text was not quite contemporaneous in origin with the other is shown by its containing some undoubted misinterpretations and misunderstandings. Its composition can, however, only be separated by a short interval from that of the Samhita, for it appears to have been known to the writer of the Aitareya Aranyaka, while its author, Çakalya, is older than both Yaska, who quotes him, and Çaunaka, composer of the Rigveda Pratiçakhya, which is based on the Pada text. The importance of the latter as a criterion of the authenticity of verses in the Rigveda is indicated by the following fact. There are six verses in the Rigveda [1] not analysed in the Pada text, but only given there over again in the Samhita form. This shows that Çakalya did not acknowledge them as truly Rigvedic, a view justified by internal evidence. This group of six, which is doubtless exhaustive, stands midway between old additions which Çakalya recognised as canonical, and the new appendages called Khilas, which never gained admission into the Pada text in any form. A further measure for preserving the sacred text from alteration with still greater certainty was soon taken in the form of the Krama-patha, or "step-text." This is old, for it, like the Pada-patha, is already known to the author of the Aitareya Aranyaka. Here every word of the Pada text occurs twice, being connected both with that which precedes and that which follows. Thus the first four words, if represented by a, b, c, d, would be read as ab, bc, cd. The Jata-patha, or "woven-text," in its turn based on the Krama-patha, states each of its combinations three times, the second time in reversed order (ab, ba, ab; bc, cb, bc). The climax of complication is reached in the Ghana-patha, in which the order is ab, ba, abc, cba, abc; bc, cb, bcd, &c. The Pratiçakhyas may also be regarded as safeguards of the text, having been composed for the purpose of exhibiting exactly all the changes necessary for turning the Pada into the Samhita text. Finally, the class of supplementary works called Anukramanis, or "Indices" aimed at preserving the Rigveda intact by registering its contents from various points of view, besides furnishing calculations of the number of hymns, verses, words, and even syllables, contained in the sacred book. The text of the Rigveda has come down to us in a single recension only; but is there any evidence that other recensions of it existed in former times?