"Phylacteries" — the outsider's name for it

The English word comes from Greek φυλακτήριον, phylaktērion — a guard, a safeguard, in practice an amulet. It reaches English through the Greek of Matthew 23:5, and it has been the standard English term for the object ever since.

It is worth naming and then setting aside, because it quietly asserts a whole theory. An amulet is worn to make something happen — to ward, to protect, to compel. That is not what the tradition holds this object is doing. Its own name, tefillin, is related to tefillah, prayer; the Torah's own word is simply totafot, of debated meaning, and the instruction attached to it is bind. A thing you tie on because you were told to is a different category from a thing you tie on because of what it will do for you.

⚠ The distinction is not merely defensive. It is the same line this app draws in every descendants' door: the moment an object becomes a device for producing effects, you are in a different tradition with different ethics. Amulets absolutely do exist in Jewish practice, in quantity, and this app has nodes about them. This is not one.