⭐ The law against crossing the sensesדברים שבכתב

Gittin 60b (and Temurah 14b), from a single verse in Exodus 34:27 that contains both channels at once — write these words, for by the mouth of these words I have made a covenant:

Words that are written, you are not at liberty to say by heart.
Words that are oral, you are not at liberty to recite from writing.

⭐⭐ Read it as a sensory rule and it is startling. The Written Torah must be seen — taken in through the eye, off a scroll, even by someone who knows every word. The Oral Torah must be heard — carried by mouth and ear, and not looked at. The prohibition is on swapping the senses.

Which is exactly what happened at Sinai, once, and is forbidden ever after.

⚠ And then the wall came down. The Oral Torah was written — the standard defence is that it would otherwise have been lost — so the book on the table is a permitted breach of its own rule. It still says come and hear. That formula is the last piece of the old mode still in place.