It's happened to everyone-- you're trying to think of a word, a name, a place, the name of a book, but you just can't bring it to mind. A friend of mine has a theory to explain this:

Inside your head is a librarian. This librarian is usually good at keeping all of the information in your head straight, but sometimes an idea gets taken off the shelf and put back in the wrong place. The best thing to do is to give your librarian a little time to do his or her job; continually interrupting to ask, "Have you found it yet?" will not help, and may just piss the librarian off.

Li*bra"ri*an, n. [See Library.]

1.

One who has the care or charge of a library.

2.

One who copies manuscript books.

Broome.

© Webster 1913.