רבינו בחיי — זאת החיה אשר תאכלו

Q — The kashrus parshiyos seem like a loose catalog: beheimos, then fish, then birds, then sheratzim. Is there a structure?

A — Rabbeinu Bachya shows the four parshiyos are an ascending diagram of the four yesodos. Sequence one (beheimos and chayos) — earth (עפר). Sequence two (fish, את זה תאכלו מכל אשר במים) — water. Sequence three (birds, ואת אלה תשקצו מן העוף) — air/ruach. Sequence four (sheratzim, וזה לכם הטמא בשרץ) — fire — and to prove this last identification, RBB points to the word למינהו added at הצב, which encodes the salamandra, the creature that lives only in fire (and dies the moment it leaves a furnace heated seven straight years). The yesod-order in Mishlei "מי עלה שמים" runs top-down (ארמ"ע: aish, ruach, mayim, afar); here in halacha the Torah inverts to bottom-up (עמר"א), starting from the heaviest yesod and rising to the most rarefied. The hierarchy of beriah is silently encoded in the order of kashrus.