Right now, that general sense of uneasiness you feel is the knowledge that you can't head over to Wikipedia and look up what year the Peloponnesian War started or find out which episode of 'Diff'rent Strokes' Nancy Reagan was on. (Answers: 431 BC and  'The Reporter.') Thanks to Wiki going dark to protest the SOPA and PIPA bills, you're likely at a loss for facts and useless trivia, wandering the streets accosting random people until someone tells you which movie Arnold Schwarzenegger costarred with Jim Belushi in. (Answer: 'Red Heat.')

But there was a time when people not only cracked heavy books to get their facts, they ordered them off TV and waited 6-8 weeks to receive them. Ladies and gentlemen, we give you the fabled "Encyclopedia Britannica."

You see, many, many years ago, if you wanted to, say, learn all about elephants, you had to order the Encyclopedia Britannica, an epic series of reference books that would be sent to you piecemeal in the mail. Yes, you got each book individually.

What if you wanted to look up "ocelots" and you just got the "A-J" volume? Too bad. Wait another 6-8 weeks. Oh, and that's after you called a 1-800 number to order the Britannica booklet which then lets you place your order for the multi-volume collection. (A day without Wikipedia doesn't seem so bad, huh?)

Children of the '90s remember a series of ads starring a geeky teenager extolling the virtues of Britannica while bantering with an omniscient narrator. (The teenager was played by Donavan Freberg, son of famed ad man and satirist Stan Freberg who voiced the deadpan narrator.) In a meta-conceit entirely lost to time, teenage Donavan started every ad by referencing the Britannica ads he starred in as a kid a decade prior. ("Remember me? I'm the kid who had a report due on space.")

Britannica is still around today as a "website," whatever that is, but we prefer to remember it as an unwieldy set of oversized books. Take a trip down memory lane with some vintage Encyclopedia Britannica ads. According to the 1985 ad, it's your "key to the information age." Because what else are you going to do until Wiki comes back? Read a book? (Update on 3/14/12: Encyclopedia Britannica has announced they are going digital-only.)