Page 507. " in that land you lost your count. There time flowed swiftly by us, as for the Elves. "
Fairies dancing in the meadow, by Nils Blommér
Public DomainFairies dancing in the meadow, by Nils Blommér - Credit: wikimedia commons

The idea that time might pass more quickly or slowly in certain magical lands is common to folklore and literature. Fairyland, Elfland, or Álfheimr in Old Norse, is a land inhabited by elves or fairies. In some stories, a short stay in Elfland is the equivalent of years in the mortal world. Other accounts warn that watching the elves dance will mesmerize a human, and he will wake to find that years have passed though it seemed like only hours. Where they dance, a ring of flowers or mushrooms might be left. This is sometimes known as a fairy-ring, and if stepped inside can whisk a mortal away to another realm.  

The strange passage of time in magical worlds can be found in many fictional works, including Tolkien’s friend C. S. Lewis’ Narnia series. In The Lion, the Witch and the Wardrobe, the children grow to adults in Narnia, but find that barely a day has passed on their return to the normal world.

Page 523. " There was an eye in the Dark Tower that did not sleep. "
Flag of Mordor
Creative Commons Attribution Share AlikeFlag of Mordor - Credit: User: Enslin

The Eye of Sauron, the symbol of the Dark Lord, indicates his unceasing vigilance and penetrating perception.  It does not have a physical manifestation other than its depiction on many of his servants' weaponry and flags.