And there was evening...and there was morning. Today.
There were a lot of ways to become unclean in the Old Testament, including many things that are impossible to avoid as a human being. And it was not just humans who became unclean - everyday things could also become unclean, just by touching the wrong things or being touched by the wrong persons. Israel spent a lot of their time trying to become clean again.
And how exactly did that happen?
It happened when they did exactly what God told them to do - go and wash, perform this ritual, sprinkle this blood, etc. But it didn't happen exactly then. See, you had to wash, or wash the item, or perform the ritual or whatever, but you would only be made clean again at evening, when God made you clean again.
Evening was the time that everything in Israelite society was reset. It was the beginning of the day, not the end of it like we know it to be. It was the time when all things were restored, right at the moment when it looked like everything was shutting down.
But that's precisely the point - at the time when everyone and everything was returning to the home for the night, God would cleanse His people and send them home. It's the same idea as not keeping your neighbor's coat overnight; he might need it. God did everything He could to make His people clean by evening, so long as they followed His commands, so that they could be inside, warm, and with loved ones when darkness fell.
Oh, how this wraps around my heart. Oh, how it gets me. Because I know the darkness, and I know the shame, and I know what it feels like to feel unclean and to desperately long for nothing more than to just. go. home. And by God's great mercy, we can.
They say His mercies are new every morning, and that's great. And in our world, it seems true. But the Old Testament reminds us that His mercies are actually new every evening, before the darkness falls.