Today we're going to go a little deeper into a very interesting she'elah (question). We said there are really two times in a day. One is called Vayehi Erev (And it was evening), and the other is called Vayehi Boker (And it was morning). Or Layla (night) v'Yom (day): nighttime and daytime. However, in halachic (according to Jewish law) terms, we spoke about the time called Bein HaShemashot, called twilight in English. In the Gemara, it is called Safek (doubt) Yom, Safek Layla. It's a doubt if it's day time, it's a doubt if it's night time.
The Aharonim (later authorities) ask a question. In Shev Shema'tata (Seven Discourses), he asks, “I don't understand. Normally, there's a concept called Chazakah. Chazakah means whatever you had before stays. If, for example, I have money in my pocket and you claim that this money is yours, there's a Chazakah. If it's in my pocket, Kol mah shebeyad adam, zeh shelo. Whatever a person has, it's his. The same concept of Chazakah applies in many different areas: as long as you don't break that Chazakah, it's like the previous status.”
So in this case, it's very simple. As long as it's day. Imagine today: now it's day. Tonight, when we're going to get to Sheki'ah (sunset), you're going to say, “At Sheki'at HaChamah, Safek Yom, Safek Layla. It's a doubt if it's day time, it's a doubt if it's night time.” Why do you have to say this is a time of Safek, when you could say the following? As long as it's not Layla Vadai (certain night), there's a Chazakah that it's Yom. As long as it's not night, you said night is at the end of twilight. As long as it's not night for sure, then there's a Chazakah. If you have a doubt if it's Yom or Layla, it's Yom, because it was Yom before it was Layla. So therefore, it is day. There shouldn't be a time of Safek. As long as it's not the next stage, then you're in the previous, you're in Yom. You're in day mode. That's the question of the Shev Shema'tata.
There are two possible answers. One answer is called Chazakah ha'asuyah lehishtanot, eina Chazakah. A Chazakah that is going to change, is meant to be changed, is not considered a Chazakah. A Chazakah is something that, if you don't change it, will stay like that. That's a Chazakah. So as long as you haven't changed it, it stays status quo. Here it's ha'asuyah lehishtanot; it's meant to be changed. For example, a Katan, somebody who's a child, is meant to be changed. There's no Chazakah that the Katan is a Katan, because when they get to 13 years old, for example, we assume that they're adults according to Torah. Well, maybe they're not. There's a Safek up until 18 years old, really. There's a Safek. Why do we consider them to be an adult? There's a Chazakah. It was a Katan before it was a Gadol (adult). Don't say it's a Katan. It's called Chazakah ha'asuyah lehishtanot, eina Chazakah. It's never going to stay a Katan forever. That we know. So a Chazakah that is meant to be changed is not considered a Chazakah. Here too, a day that you know will become night, inevitably, every 12 hours it will become night at one point. It's not considered a Chazakah to impose a daytime until you know that it's nighttime. So there could be a Safek because Chazakah ha'asuyah lehishtanot eina Chazakah.
Another possible answer is the following: really, there's no daytime, by definition. What makes the day day is the fact that there's light from the sun. If that's the definition of day, it means that every second you could actually... Is it day or night? Day. Is it day or night? Day. Is it day or night? Day. Why? Because there's a ray of sun. Well, the second you don't have the ray of sun anymore, which is at the time of Sheki'at HaChamah, at the time of sunset, you don't have that definition of day anymore. And that's what creates the Safek: is it day or is it night? It's light, but there's no ray of sun. And therefore, I don't have that definition of day in order to make it a day. There's no Chazakah or no Chazakah in this case. It's about what's going on right now. Is there a day or not? Is there sun or not? As long as I have sun, I know it's day. There's no more sun, I know it's not day. And therefore, I don't know what it is. And that's why there's a time called Bein HaShemashot, because Hashem in the coming days will study the halachot (laws) of that very interesting time called Bein HaShemashot.