This question is asked at a very basic level, not deeply aware of Judaism or the process of Jewish law. I'm not Jewish so it isn't directly applicable to me, but it helps me to ask a broader question I have by anchoring it to something specific.

I read in the Talmud, Berachot 2a, about the time from which a person can say Shema in the evening. It's connected to the words in Deuteronomy to remember God's commandments when you're lying down and when you're getting up. I can see the connection, and the way in which saying this prayer helps both individuals and your community (together) to remember and fulfil the letter and spirit of this integral instruction. I also understand some of the reasons individuals should do what the community is doing (and was doing in the times of the Talmud's redaction), in things like this. What I'm confused about is the stretch from simply saying it whenever you go to bed to this whole concern of deciding what time is appropriate to do so every day. The Gemara asks why the question 'from what time' was brought, but the answer isn't given on the level that I'm wondering about.

Maybe there's an opportunity here for me to learn something about the process of passing on and working with the oral law. Do you think this interest with times is a 'fence' measure to make sure a Torah law (to say Shema) is kept, similarly to the statement in the mishnah about why the sages said 'until midnight'? Or do you think this practice or saying Shema itself emerged not from a Torah law per se, but from a desire by the priests and leaders to create a tradition that would allow clear memory of and commitment to the things spoken of in Deuteronomy; and then times were also given? Or do you think that Shema was said at particular times from the days of Moses, and that the mishnah here was recording something original to the oral Torah? How much can we say about the background behind these things? If not much can be known about the history of it, then it doesn't matter, but I want to know if I'm missing something.

I'd value hearing more about how rabbinic tradition handles things like this, to come to the decisions you have before you today, with reference to this particular question. What is the connection between what is written in the verses and what is passed down through the generations, here?