Have you ever played the game
Ocarina of Time for the
Nintendo 64? Well, let me explain a bit. This game involves a
ocarina, which your main character
Link, can learn songs for. Playing the songs causes various magical effects to occur.
You can also travel through time, from when Link is a child to when he is an adult, and back. In one of towns, there is a large
windmill. If you go there as an adult, and talk to the proprietor, he will teach you
The Song of Storms, which some kid with an
ocarina played several years ago that summoned huge storms and destroyed the windmill.
If you now travel back in time, go to the same windmill, and play The Song of Storms, you will summon huge storms and destroy the windmill, and the proprietor will ask "Where you did learn that song?! Argh! I'll never forget it now!"
The burning question, though is where did the song come from? Apparently, the song just appeared out of nowhere. Tho proprietor taught it to Link who taught it to the proprietor who taught it to Link who taught it to the proprietor who taught it to Link who taught it to the proprietor who taught it to Link who taught it to the proprietor who taught it to Link...(see recursion)
A more homey example would be if you were creating a password to convince yourself you have traveled back in time. Let's say PSelf gets a call from FSelf, and despite PSelf not having had the good fortune to read said E2 node yet, FSelf is a very persuasive speaker and convinces PSelf not to press the button. PSelf decides this would be a good time to remember that password, just in case he ever needs it again. Whew.
Now, where did the password come from? It just appeared recursively out of the folds of time! FSelf taught it to PSelf who taught it to FSelf who taught it to PSelf who taught it to FSelf who taught it to PSelf who taught it to FSelf who taught it to PSelf who taught it to FSelf who taught it to PSelf who taught it to FSelf who...you get the idea.
So, next time you go time traveling, don't be afraid to leave one of these cool little easter eggs, they're fun fun fun!