Truly, the heaven-bound boat is the Agnihotra sacrifice. The two sides of that heaven-bound boat are the Ahavaniya and the Garhapatya altars. Truly, the steersman of the boat is the milk-pouring priest.The above quote is from the Satapatha Brahmana, which is associated with the White Yajurveda, and is wirtten in Vedic Sanskrit. It is part of the shruti, or "heard" texts, being ascribed divine origin.-Satapatha Brahmana 126.96.36.199
Truly, unsteady ships are those which take the form of sacrifice: The eighteen [older sacred texts] in which the lesser [form of] action is stated. Those fools who praise this [doctrine] as better [than that which is revealed here], Truly they go again to old age and death.This quote is from the Mundaka Upanishad, associated with the Atharvaveda (the latest of the Vedas). It is from a later linguistic period than the SB (the language is Classical Sanskrit), and relegates the four vedas (along with many sciences and even poetry) to "lower knowledge" and attempts to explain "higher knowledge" and denigrate the "lower" sources of knowledge. (The bracketed additions, for those interested, are from Bruce Lincoln, but are consistent with what I read.)-Mundaka Upanishad 1.2.7
It's clear that the two passages (probably not written temporally far apart) are in conflict. This may be because of their subject matter: the Yajurveda is maybe two to five hundred years older than the Atharvaveda, which shows a focus on magic for protection, cures and curses, rather than the Yajurveda's focus on religious ritual. It may also be because of their author (ignoring for a moment that the Brahmanas are shruti): the Brahmana was probably composed by a priest, and the Upanishad probably was not, meaning that propping up the priesthood was in the best interest of the Brahmana, while kicking it when it was down was in the best interest of the Upanishad.
I've been kicking these quotes around for a while, reading them and re-reading them, viewing them in context and out of context.
First, we're told that the way to heaven is through sacrifice, and that the person who can get you there most reliably is the brahman (priest). This is purely action: do the act, and you are assured of your place in the cosmos.
Next, though, we are told that there is nothing awaiting the person who performs these "lesser" acts, except "old age and death." Reading on in that Khanda, we are informed that it is through rejection of the material world (having no house, living in poverty, and being without desire) will you attain "Brahman" (a capital "B" Brahman is different than a lower-case "b" brahman).
Interestingly, while the first one says "Pay a priest to make sacrifices for you" (implying that they know what they're doing and will help you arrive safely, even though you can do it yourself), the second one eventually goes on to say, "Since you can't get there with a priest, go find yourself a Guru, and maybe you can get in. If you're perfect."
Side Note, unrelated but cool: according to the Mundaka Upanishad, the seven tongues of fire are called: Kâlî (black), Karâlî (terrific), Manogavâ (swift as thought), Sulohitâ (very red), Sudhûmravarnâ (purple), Sphulinginî (sparkling), and the brilliant Visvarûpî (having all forms)