Symbolism, Imagery, Allegory
Shine A Little Light On Me
The first thing Lucy sees in the snowy woods of Narnia is...a lamppost. A plain ol', boring ol' lamppost. (If you're wondering how the lamppost got there, well, you'll have to read The Magician's Nephew…we know it's kind of irritating that we keep mentioning it, but it is the prequel, so it answers all sorts of questions.)
In The Lion, the Witch, and the Wardrobe, the lamppost functions as a beacon in more ways that one—showing the children the way to Narnia when the come into it from our world, and showing them the way back when they need to leave. At the end of the adventure, it's the lamppost which leads the way home for the children, triggering their memories of their old lives in England.
The lamppost is an object that isn't quite Narnian and isn't quite a part of the "real world." Narnia is pseudo-medieval, so the lamppost is anachronistic. But the Pevensies' come from the England of the 1940's, and the lamppost is outdated by 1940's standards—it has a flame burning in it rather than an electric bulb. It exists out of time and place, which is why it so efficiently signals to the children (and later, to the queens and kings) that something is off.
If all these things didn't make it important enough, the lamppost also causes Edmund to slip up and prove to Peter and Susan that he lied about his first trip to Narnia—the fact that he knows which way to go to find it proves he has been there before. Yup; this lamppost sheds light on pretty much everything...including lies.