Do you ever have those days where you come up with the most amazing thought? You go to write it down, but by the time you get to your notebook, find something to write with and flip open to an empty page, the thought is gone? Yeah, I just had that happen to me earlier. I've been trying to run though everything that has happened today in hopes that it would spark the idea up again, but so far I'm running into a brick wall with each attempt.
I used to carry a little pocket notepad with me all of the time for the very purpose of writing things down that I knew I might forget. Everything from simple things to pick up at the store to big ideas to near future todo lists to how I plan on taking over the world.
The brain only remembers things it absolutely needs to in order to get by. Some of us are cursed with having really useless knowledge that might help us in a game of Trivial Persuit or to bore someone to death by. Sometimes, the brain can be working when you least expect it to and actually comes up with something useful. If you don't do something immediately with what the brain has provided, it discards it as useless information.
Just a reminder. Keep something to write with and to write on within reach at all times and things like this won't happen.