Evolving Practices (Was: Kiddushin and Nisuin

On Thu, Sep 18, 2025 at 09:51:27AM EDT, R Akiva Miller commented on a
quote by RYGB about the shift to making eirusin and nisuin back-to-back:

This makes a lot of sense. The paucity of tangible records
of the evolution of the practice remains remarkable.

I'm not sure, but I think RYGB is pointing out that we do have records
regarding the evolution of most *other* practices....

I'd like to suggest that Heseba might be another example of this. It seems
that there was a universal style of eating meals which involved
individuals, each with their own recliner-couch and small table...

I am not sure the cases are comparible. Is heseibah at a non-Seder meal
an issue of din or minhag? Or was it that societal norms changed causing
a new scenario to pasqen about?

...

If R [Aryeh Frimer] is correct about blaming Kiddushin/Nisuin on the
Crusades, then it would be an example of...

There is another case where the Crusades forced a change in Minhag, and
I also don't know a paper trail -- angling the Mezuzah. Ashkenazim went
from holding like Rashi (and the Rambam) to holding like both them and
Rabbeinu Tam with no record of the switch.

(And yes, diagonoal is a "both", not a compromize. The gemara says
one shouldn't post a mezuzah "like a nagar". And the diagonal is not
like anyone's definition of what that means.)

In terms of history, we saw three stages:
1- Before the Crusades: vertical.
2- During the Crusades: Many doorways were found where the notch the
   mezuzah was in was turned into a cross. When a Jewish home was
   appropriated (hopefully the previous owners survived) the new
   Christian residents would pick out the mezuzah, which was vertical,
   and put a horizontal notch across it to make a cross. (Or maybe the
   problem was worse and that they didn't tear out the mezuzah first?)
3- Late Crusades and after: diagonal.

Chodesh Tov!
Tir'u baTov!
-Micha