I spy with my little eye...(wordplay)

"I spy with my little eye..."
: : Could anyone explain to me the meaning of this wordplay? And what is the origin of this line? 

Is a children's guessing game. The game I Spy originated in the early 20th century. It remains a common pastime played by children - albeit often initiated by adults to occupy bored children on car journeys and the like. One person secretly choose an object that they can 'spy with their little eye' and the others take turns to guess the name of the object.

In the original version of the game, one player would say, "I spy, with my little eye, something beginning with A [or any other letter of the alphabet]". The other player or players would look around them and try to guess what the thing beginning with A might be. (It had to be something that was really there and that everyone could see.) The person who guessed what it was, could then choose another thing and for the other players to guess.