I like this bit.
A 15th century Byzantine manuscript with many kabbalistic items. In the margins of Azriel of Gerona’s commentary to Sefer Yetsirah, someone wrote:
גוזר אני עליך שלא תלמוד בו עד היותך בן ל’ שנים
I forbid you to study this until you are 30 years old.
Maybe he had someone specific in mind. Maybe it was just a general warning. Especially since the manuscript used to belong to an Italian Jewish community.