The hymns of the eighth book in general show a mutual affinity hardly less pronounced than that to be found in the family books. For they are connected by numerous repetitions of similar phrases and lines running through the whole book. The latter, however, does not form a parallel to the family books. For though a single family, that of the Kavas, at least predominates among its authors, the prevalence in it of the strophic form of composition impresses upon it a character of its own. Moreover, the fact that the eighth book contains fewer hymns than the seventh, in itself shows that the former did not constitute one of the family series.
The first part (150) of Book I. has considerable affinities with the eighth, more than half its hymns being attributed to members of the Kava family, while in the hymns composed by some of these Kavas the favourite strophic metre of the eighth book reappears. There are, moreover, numerous parallel and directly identical passages in the two collections. It is, however, at present impossible to decide which of the two is the earlier, or why it is that, though so nearly related, they should have been separated. Certain it is that they were respectively added at the beginning and the end of a previously existing collection, whether they were divided for chronological reasons or because composed by different branches of the Kava family.
As to the ninth book, it cannot be doubted that it came into being as a collection after the first eight books had been combined into a whole. Its formation was in fact the direct result of that combination. The hymns to Soma Pavamāna (the clearly flowing) are composed by authors of the same families as produced Books II.VII., a fact, apart from other evidence, sufficiently indicated by their having the characteristic refrains of those families. The Pavamāna hymns have affinities to the first and eighth books also. When the hymns of the different families were combined into books, and clearly not till then, all their Pavamāna hymns were taken out and gathered into a single collection. This of course does not imply that the Pavamāna hymns themselves were of recent origin. On the contrary, though some of them may date from the time when the tenth book came into existence, there is good reason to suppose that the poetry of the Soma hymns, which has many points in common with the Avesta, and deals with a ritual going back to the Indo-Iranian period, reached its conclusion as a whole in early times among the Vedic singers. Differences of age in the hymns of the ninth book have been almost entirely effaced; at any rate, research has as yet hardly succeeded in distinguishing chronological stages in this collection.
With regard to the tenth book, there can be no doubt that its hymns came into being at a time when the first nine already existed. Its composers grew up in the knowledge of the older books, with which they betray their familiarity at every turn. The fact that the author of one of its groups (2026) begins with the opening words (agnim īḷe) of the first stanza of the Rigveda, is probably an indication that Books I.IX. already existed in his day even as a combined collection. That the tenth book is indeed an aggregate of supplementary hymns is shown by its position after the Soma book, and by the number of its hymns being made up to that of the first book (191). The unity which connects its poetry is chronological; for it is the book of recent groups and recent single hymns. Nevertheless the supplements collected in it appear for the most part to be older than the additions which occur in the earlier books.
There are many criteria, derived from its matter as well as its form, showing the recent origin of the tenth book. With regard to mythology, we find the earlier gods beginning to lose their hold on the imagination of these later singers. Some of them seem to be disappearing, like the goddess of Dawn, while only deities of widely established popularity, such as Indra and Agni, maintain their position. The comprehensive group of the Viçve devās, or All gods, has alone increased in prominence. On the other hand, an altogether new type, the deification of purely abstract ideas, such as Wrath and Faith, now appears for the first time. Here, too, a number of hymns are found dealing with subjects foreign to the earlier books, such as cosmogony and philosophical speculation, wedding and burial rites, spells and incantations, which give to this book a distinctive character besides indicating its recent origin.
Linguistically, also, the tenth book is clearly distinguished as later than the other books, forming in many respects a transition to the other Vedas. A few examples will here suffice to show this. Vowel contractions occur much more frequently, while the hiatus has grown rarer. The use of the letter l, as compared with r, is, in agreement with later Sanskrit, strikingly on the increase. In inflexion the employment of the Vedic nominative plural in āsas is on the decline. With regard to the vocabulary, many old words are going out of use, while others are becoming commoner. Thus the particle sīm, occurring fifty times in the rest of the Rigveda, is found only once in the tenth book. A number of words common in the later language are only to be met with in this book; for instance, labh, to take, kāla, time, lakshmī, fortune, evam, thus. Here, too, a number of conscious archaisms can be pointed out.
Thus the tenth book represents a definitely later stratum of composition in the Rigveda. Individual hymns in the earlier books have also been proved by various recognised criteria to be of later origin than others, and some advance has been made towards assigning them to three or even five literary epochs. Research has, however, not yet arrived at any certain results as to the age of whole groups in the earlier books. For it must be borne in mind that posteriority of collection and incorporation does not necessarily prove a later date of composition.
Some hundreds of years must have been needed for all the hymns found in the Rigveda to come into being. There was also, doubtless, after the separation of the Indians from the Iranians, an intermediate period, though it was probably of no great length. In this transitional age must have been composed the more ancient poems which are lost, and in which the style of the earliest preserved hymns, already composed with much skill, was developed. The poets of the older part of the Rigveda themselves mention predecessors, in whose wise they sing, whose songs they desire to renew, and speak of ancestral hymns produced in days of yore. As far as linguistic evidence is concerned, it affords little help in discriminating periods within the Rigveda except with regard to the tenth book. For throughout the hymns, in spite of the number of authors, essentially the same language prevails. It is quite possible to distinguish differences of thought, style, and poetical ability, but hardly any differences of dialect. Nevertheless, patient and minute linguistic research, combined with the indications derived from arrangement, metre, and subject-matter, is beginning to yield evidence which may lead to the recognition of chronological strata in the older books of the Rigveda.
Though the aid of MSS. for this early period entirely fails, we yet happily possess for the Rigveda an abundant mass of various readings over 2000 years old. These are contained in the other Vedas, which are largely composed of hymns, stanzas, and lines borrowed from the Rigveda. The other Vedas are, in fact, for the criticism of the Rigveda, what manuscripts are for other literary monuments. We are thus enabled to collate with the text of the Rigveda directly handed down, various readings considerably older than even the testimony of Yāska and of the Prātiçākhyas.
The comparison of the various readings supplied by the later Vedas leads to the conclusion that the text of the Rigveda existed, with comparatively few exceptions, in its present form, and not in a possibly different recension, at the time when the text of the Sāma-veda, the oldest form of the Yajur-veda, and the Atharva-veda was constituted. The number of cases is infinitesimal in which the Rigveda shows a corruption from which the others are free. Thus it appears that the kernel of Vedic tradition, as represented by the Rigveda, has come down to us, with a high degree of fixity and remarkable care for verbal integrity, from a period which can hardly be less remote than 1000 B.C.
It is only natural that a sacred collection of poetry, historical in its origin, and the heritage of oral tradition before the other Vedas were composed and the details of the later ritual practice were fixed, should have continued to be preserved more accurately than texts formed mainly by borrowing from it hymns which were arbitrarily cut up into groups of verses or into single verses, solely in order to meet new liturgical needs. For those who removed verses of the Rigveda from their context and mixed them up with their own new creations would not feel bound to guard such verses from change as strictly as those who did nothing but continue to hand down, without any break, the ancient text in its connected form. The control of tradition would be wanting where quite a new tradition was being formed.
The criticism of the text of the Rigveda itself is concerned with two periods. The first is that in which it existed alone before the other Vedas came into being; the second is that in which it appears in the phonetically modified form called the Saṃhitā text, due to the labours of grammatical editors. Being handed down in the older period exclusively by oral tradition, it was not preserved in quite authentic form down to the time of its final redaction. It did not entirely escape the fate suffered by all works which, coming down from remote antiquity, survive into an age of changed linguistic conditions. Though there are undeniable corruptions in detail belonging to the older period, the text maintained a remarkably high level of authenticity till such modifications as it had undergone reached their conclusion in the Saṃhitā text. This text differs in hundreds of places from that of the composers of the hymns; but its actual words are nearly always the same as those used by the ancient seers. Thus there would be no uncertainty as to whether the right word, for instance, was sumnam or dyumnam. The difference lies almost entirely in the phonetic changes which the words have undergone according to the rules of Sandhi prevailing in the classical language. Thus what was formerly pronounced as tuaṃ hi agne now appears as tvaṃ hy agne. The modernisation of the text thereby produced is, however, only partial, and is often inconsistently applied. The euphonic combinations introduced in the Saṃhitā text have interfered with the metre. Hence by reading according to the latter the older text can be restored. At the same time the Saṃhitā text has preserved the smallest minutiæ of detail most liable to corruption, and the slightest difference in the matter of accent and alternative forms, which might have been removed with the greatest ease. Such points furnish an additional proof that the extreme care with which the verbal integrity of the text was guarded goes back to the earlier period itself. Excepting single mistakes of tradition in the first, and those due to grammatical theories in the second period, the old text of the Rigveda thus shows itself to have been preserved from a very remote antiquity with marvellous accuracy even in the smallest details.
From the explanatory discussions of the Brāhmaas in connection with the Rigveda, it results that the text of the latter must have been essentially fixed in their time, and that too in quite a special manner, more, for instance, than the prose formulas of the Yajurveda. For the Çatapatha Brāhmaa, while speaking of the possibility of varying some of these formulas, rejects the notion of changing the text of a certain Rigvedic verse, proposed by some teachers, as something not to be thought of. The Brāhmaas further often mention the fact that such and such a hymn or liturgical group contains a particular number of verses. All such numerical statements appear to agree with the extant text of the Rigveda. On the other hand, transpositions and omissions of Rigvedic verses are to be found in the Brāhmaas. These, however, are only connected with the ritual form of those verses, and in no way show that the text from which they were taken was different from ours.
The Sūtras also contain altered forms of Rigvedic verses, but these are, as in the case of the Brāhmaas, to be explained not from an older recension of the text, but from the necessity of adapting them to new ritual technicalities. On the other hand, they contain many statements which confirm our present text. Thus all that the Sūtra of Çānkhāyana says about the position occupied by verses in a hymn, or the total number of verses contained in groups of hymns, appears invariably to agree with our text.
We have yet to answer the question as to when the Saṃhitā text, which finally fixed the canonical form of the Rigveda, was constituted. Now the Brāhmaas contain a number of direct statements as to the number of syllables in a word or a group of words, which are at variance with the Saṃhitā text owing to the vowel contractions made in the latter. Moreover, the old part of the Brāhmaa literature shows hardly any traces of speculations about phonetic questions connected with the Vedic text. The conclusion may therefore be drawn that the Saṃhitā text did not come into existence till after the completion of the Brāhmaas. With regard to the Ārayakas and Upanishads, which form supplements to the Brāhmaas, the case is different. These works not only mention technical grammatical terms for certain groups of letters, but contain detailed doctrines about the phonetic treatment of the Vedic text. Here, too, occur for the first time the names of certain theological grammarians, headed by Çākalya and Māūkeya, who are also recognised as authorities in the Prātiçākhyas. The Ārayakas and Upanishads accordingly form a transition, with reference to the treatment of grammatical questions, between the age of the Brāhmaas and that of Yāska and the Prātiçākhyas. The Saṃhitā text must have been created in this intermediate period, say about 600 B.C.
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 Saṃhitā, gives each separate word in its independent form, and thus to a considerable extent restores the Saṃhitā 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 Saṃhitā, for it appears to have been known to the writer of the Aitareya Ārayaka, while its author, Çākalya, is older than both Yāska, who quotes him, and Çaunaka, composer of the Rigveda Prātiçākhya, which is based on the Pada text.