What is the origin of the Sabbath, and when and how did people first know to observe it?

So I don't think it's a stretch to understand that God, even after Adam's sin, taught the men that were then living that the seventh day is the Sabbath. I mean, because He made a big deal of it during the creation week. Adam knew what the seventh day was. He's made on the sixth day and on the seventh day he rested, and I'm sure God told him that the previous five days before the sixth day, God was creating the rest of the universe. And he thought, wow, I'm the beginning of this. No, there were five days before you. You're the sixth day. And so Adam had that in his mind. He knew that every seventh day was a Sabbath day. So that's where it's coming from. And so all this tracing of the Sabbath you did, through the Israelite sojourn or the seventh day in the creation, it's all because Adam is experiencing the Sabbath himself, that everybody else is going to know about it. And they're going to be required to rest on the Sabbath. That's going to be a law to rest on the Sabbath. He works six days and rests the seventh. And those who disobey that... There used to be things called blue laws in our society back in the 40s, 50s. Then we lost all that from the 60s onward. And there's still some businesses that stop working on the Sunday, which was now our seventh day. It's the first day. Because that concept has just been ingrained since man was created. So it takes a lot to take it out of society, but when the society does take it out, they begin to fall apart. There's something about that seventh day. And this is a lesson for us Catholics. If you find yourself working on the seventh day, that is now the first day of the week, Sunday, first of all, go read your catechism. It'll tell you not to be working and to do some spiritual things on Sunday, okay? So you're not working and you're not supposed to be making anybody else work. So we have to be very careful about that. Because it's very easy to let the society go and think, oh, you can work any day you want. Nope. People are working on Sunday. So let's do a double check on our lives and make sure that no work is done on Sunday.