Song of the Day

Sometimes a song just gets attached with the tongue. You will get just attached with the song. It just repeats it self, no matter what!
I call it Song of the Day. Because it just stays around your mouth for the day.
Sometimes it happens that you will come across some thoughts, some beautiful ideas, and some interesting ideas. It is just like flash. It just comes and goes away.  I witnessed this fact when I had written a fresh article, later to find that it had already been sketched in my old pages of diary. If you can catch it, its caught forever; if it is missed it is like a big fish!
So, these are two processes: one has some long term effect while the other has very short term effect.

Mind can catch the melody and songs while it gets away with the philosophical thoughts.
But I have a feeling that some beautiful thoughts are saved somewhere in our mind. It may come into our thoughts when you are indulged in something else. May be in rest-room, may be in the middle of telephone conversations, while standing inside the bus or while sleeping. If we suppose our state of mind to be taking a kind of random walk, I think it is like coming to some spot in the brain. (Just like finding a simple pole in complex plane.)
The question is how does the brain store the memory?
and how does the random thoughts occur?