For the record, I was referring to the ideas that rebirth is just thrown into the Upaniṣads and does not fit in, that no such ideas are expressed pre-Upaniṣad, etc. The RgVeda, as I said, is another matter. I would say that it is very clear that there are several passages referring to rebirth once one is familiar with the philosophical context of the RgVeda, and I will quote some below (@Meggers has already quoted a passage). Also, it is somewhat of a ‘big ask’ to ask for a clear, abstract, philosophical statement about the nature of the afterlife process in the RgVeda—these types of texts are simply not how the RgVeda operates. But either way, as I said several times, the Jaiminīya Brāhmaṇa contains a description of two paths of the afterlife with rebirth, and the Brāhmaṇas were the main texts that schools of brahmins used and compiled for understanding ritual/exegesis, etc. The descriptions in the JB, JUB, CU, BĀU, etc., no surprise, all have rebirth doctrines that match up with what we see in the RgVeda—people going to astral bodies from cremation fires, being converted into food/water, eventually brought back for people to give birth to them.
Also, the paper I sent is a short excerpt analyzing a few portions of the RgVeda. Joanna Jurewicz, in her ~450 pg. monograph on the RgVeda which is extremely well esteemed, has two entire chapters dedicated to the afterlife/sacrifice in the RgVeda with several different sections of the 10th mandala referring to rebirth and also how these ideas are integrated throughout the entire philosophical system of the text itself. Other chapters elaborate some of these ideas as found in other sections of the text. I would recommend reading that (Fire and Cognition in the RgVeda) and then ‘Fire, Death, and Philosophy’ which discusses the RgVeda, Atharvaveda, Brāhmaṇas and early Upaniṣads. These texts cannot just be quoted and understood at face value; they take detailed analysis and deconstruction (again, unlike the Buddhist suttas for instance which make much clearer philosophical statements in abstract terminology).
In the 10th Mandala, people are cremated, rise up to the sun (which is understood as a cosmic sacrificial fire), drink Soma/enjoy ultimate bliss, and then become the oblation in that same Sun-fire in the form of rain falling back to earth. This is found all throughout RV 10.16 and RV 10.14.8. I will not use it as “evidence” because understanding the RgVeda takes hundreds of pages of analysis, not a simple quotation. Instead, I will quote from the Brāhmaṇas which spend lots of words on describing the rebirth process. Nevertheless, this is a more “abstract” passage that is not filled with such complicated metaphor:
sáṁ gachasva pitÉbhiḥ sáṁ yaméneṣṭāpūrténa paramé vyòman |
hitváyāvadyám púnar ástam éhi sáṁ gachasva tanvã suvárcāḥ || (10.14.8)
Unite with fathers, unite with Yama, with sacrifices and good deeds in the
highest heaven! Leaving evil, come back again to the house, unite with your
body, o beautifully radiant!
Jurewicz (2010) builds on what Renou (1956) thought in agreeing that this is probably in reference to rebirth after drinking Soma on the Sun. One comes back to their body having been purified and essentially cleansed by the heat of the Sun (as is a common Vedic theme).
JB 1.17-18 and 1.45-50 are where we see descriptions of the Five Fires and afterlife paths with rebirth.
I will quote just one relevant section from JB 1.45 from Bodewitz (1973). There is simply too much material to quote it all on the forum here.
Man is Agni Vai£vanara. Its fuel is speech, its flame sight, its smoke breath, its sparks mind, its coals hearing. In this same Agni VaiSvanara the gods day by day offer food. From this oblation when it has been offered seed [semen] comes into existence.
Woman 7 is Agni Vai^vanara. Its fuel is the vagina, its flame the vulva, its smoke desire (?), 8 its sparks the feelings of enjoyment, its coals the coitus. In this same Agni VaiSvanara the gods day by day offer seed. From this oblation when it has been offered man comes into existence.
Thus in this fifth creation man is born from the gods. At the fifth creation the divine waters speak with a human voice. 9 And when* he goes to yonder world —
46 — his (funeral) fire is Agni VaiSvanara. Its fuel is the herbs and trees, its flame is just the flame (of the fire), its smoke just the smoke, its sparks just the sparks, its coals just the coals. In this same Agni VaiSvanara the gods day by day offer man. From this oblation when it has been offered man comes into existence (and goes) to yonder world. 10 That is for him the world in which he resurges.
Of that god who shines here 11 night and day, the half-months, the months, the seasons and the year are the guards. Night and day are forerunners (who announce his coming). 12 To 13 him one of the seasons, who has a hammer in his hand, 14 comes down along a ray of light and asks him: “Who art thou, man?” 13 In case he has some (but not the perfect) knowledge he may withhold (his name from the interrogator). 16 Then he strikes at him (with his hammer). Of him when he has been stopped the good works disappear in three parts. 16 He (i.e. the Rtu) takes one third. One third diffuses in the air. Together with one third he (i.e. the deceased) descends in the direction of this world. 17 The world which is won by him on account of his gifts, in that he stops. Thereupon even him Death ultimately reaches. Repeated dying is not overcome by him who 18 knows (only) thus.
There is much more in depth analysis of all of this and the other passages that relate to it throughout the text of course from many scholars, and it has long been uncontroversial that this is all about rebirth (the above passage being just one excerpt from one section of the text).
The model of Five Fires is the model of reality conceived in terms of cycles of sacrifice. We find this to explain rebirth in the earliest Upaniṣads as well (BU, CU, KU, JUB, etc.). Basically, there are fires and oblations. In JB 1.4, the fires are: sun, thunder, earth, man, woman. The oblations which are “offered” into these metaphorical fires are: immortality and water, king Soma, rain, food, and semen. When an oblation is offered into one fire, the heat transforms it into the next sacrifice in the line of fires. So for instance, food is offered into man (digested in his stomach), which turns into semen offered into woman. This then forms a cycle of sacrifice in how the world operates. The next one is the cremation pyre (into which man is offered), and from there rises to the Sun (the first in the list) via smoke of the fire. Notice that the person being offered into the sun is “immortality and water” (which is consistent with other Vedic conceptions), and yet this is a cycle of rebirth. “Amrta” (deathlessness/immortality) is not necessarily the state of the person—who will be reborn—but the immortal state to which they temporally go and join their fathers/the Sun. There is a possibility to join the Sun permanently though as well (and thus this would be a permanent form of heaven). Jurewicz (2016) summarizes the two paths:
From what has been said it follows that the JB presents two possibilities for the afterlife which the BU and CU will elaborate more precisely. The first possibility ends with a return to the state of life and death and the second in union with the sun. There are three factors on which the afterlife depends. The first is the deeds deceased performed during his life. The second is knowledge of one’s origin. The third is somehow connected with a properly performed cremation.
Jurewicz (2016), in conclusion to this section of the JB, writes:
Bronkhorst (2007) claims that the difference between the earlier Vedic thought and the culture of Magadha is the belief in transmigration which in the next incarnation depends on previous deeds. He claims that such a belief is not attested in the early Veda (2007: 115). Taking into account the evidence of the JB, the problem is more complex. According to this text, the future incarnation depends on deeds. Firstly, it depends on gifts the deceased gave during his life (in the first path). Secondly, it depends on deeds of those who are still alive and can perform the proper cremation rite (in the second path). This line of thinking is continued in the JUB (see section 5.2). It is worthwhile mentioning that even in the ṚV the concept of deeds (iṣṭāpūrtá, ṚV 10.14.8), which unite with the deceased in the sun, imply their influence on him. … The two possible ways of the deceased are seen as the result of the proper performance of the Agnihotra and the cremation rite. This also weakens Bronkhorst’s hypothesis about the non-Brāhmaṇical source of a belief in rebirth.
The same ideas are continued in the JUB, which is usually understood as an Āraṇyaka (rather than an Upaniṣad) despite what the name seems to suggest, and dates to the Brāhmaṇa period. There, rebirth is also explicitly defined and explained in complex ways via the Five Fires model (and with 3 afterlife paths, as opposed to just two in the JB which relate to knowledge/performance of ritual). JUB 3.13-14 describes how people ascend to the immortal world of heaven/the Sun as per usual, and then how from there they come to be re-born in the human womb and so on via good deeds. All of this is again consistent with the general philosophy of the RgVeda and the specific passages alleged to be about rebirth, and also with the thought of the Brāhmaṇas themselves (rather than some super-imposed external belief). Even the travel path the deceased take through astral bodies and so forth calls on the same passages in RgVeda 10.16.
In my previous post, I discussed how the nature of reality presented in the ŚB in a way necessitates there be some form of rebirth as at least a possibility or factor of existence for some people. Jurewicz (2016) sees the same thing and says the following:
As I have shown elsewhere (Jurewicz 2004), the successive stages of functioning of the cosmos can be seen as the successive acts of offering milk into fire which repeats the first creative act of Prajāpati in which he offered milk to fire and thus redeemed himself from total annihilation (ŚB 2.2.4, see chapter 3.1.1). Viewed from this perspective, the model of the Five Fires presents the functioning of the cosmos in terms of Agnihotra which ensures the safe manifestation of Prajāpati within its frames. There is a close similarity between Prajāpati who creates fire from himself and the sacrificer who, in the Agnyādheya rite, kindles fires which are identified with his breaths, i.e. with his self (JB 1.1-2)28. In this fire-self the sacrificer has to perform the Agnihotra in order to obtain long life and immortality after death as Prajāpati did in illo tempore and does all the time in order to manifest himself as the cosmos. It is worth adding that in the model of the Five Fires the composer of JB 1.45 uses the word visr̥ ṣṭi in reference to the cosmic sacrifices as if he wanted to emphasise the creative role of the processes described in the model.
Gregory Shushan, in the article I posted, also lists many examples from the ŚB that agree with different afterlife paths, some involving being burnt by the sun (offered in oblation→rebirth), impermanence in afterlife realms, etc. as is again expected. This again confirms that the model of the Five Fires / constant sacrifice in relation to rebirth specifically is completely at home within the Brahmanical tradition. Time and again we see how ritual prepares one for the afterlife where there is travel among different bodies or perhaps cycles of cosmic sacrifice, and how one may be reborn in a womb or on earth, or perhaps admit into some kind of eternal existence, perhaps even be annihilated. There is a degree of freedom and choice for those who know the Veda and performed good karma, and rebirth among ancestors or existence in the manifest aspect of reality seem to be occasionally perceived as a positive expression of one’s immortality (as opposed to Upaniṣadic ideas where transcending into the unmanifest aspect is an escape from rebirth into a state of immortality they come to perceive as superior). There are certainly a plethora of ideas, though!
Mettā!