When I was in grammar school, I was slow to get my stuff together to go home and the janitor (they were called that then) would come in and with a sponge and a bucket of water would wash the blackboard. All the muck from the day would be gone, including all the chalk dust (except at the corners). Poof... just like that!
The Buddhists used to think of night as the beginning of the next day. And when we are born our minds are blank. As we live, our minds become repositories for all our numerous experiences. Loves come in and out and cements those experiences.
Then, at the end, we don't want to go home, so we take our time. Before we know it, the funny old janitor comes in and washes the blackboard. Our day's toil is now a clean slate.
Our tears for such a beautiful one ready us for another day... and another life.