The "Sieve and the Sand" refers to two incidents: one from Montag's childhood and one from the present. In the incident from his childhood, a cousin challenged Guy Montag to fill a sieve with sand in exchange for a dime. Of course, the more sand that the child Montag put into the sieve, the more sand fell through the holes in the sieve. This frustrated Guy, causing him to cry. The other incident involves Montag's attempts to memorize. He is trying to commit to memory the Book of Ecclesiastes from the Bible, but the jingle from the advertisement for Denham's Dentrifice that keeps playing while Montag is on the train is interfering and the words to Ecclesiastes fall through his memory just like the sand went through the sieve all those years ago. Just as he was as a child, Guy Montag is frustrated at his inability to hang onto the words he's trying to memorize. Guy's modern world counts on this inability to concentrate. This world he lives in without books has encouraged people to live for the immediate moment; it's a world of sound bites and expediency. By filling every place with mindless sound such as the advertisement jingle, people can't concentrate and do any serious thinking. If people can't think, they are much more easily controlled. This is just where society, and the government in the book, want people. By banning books, people's minds have been turned into sieves unable to hold thought.
I think that both answers are correct... Im a sixth grader and I AM IN LOVE WITH THIS BOOK!!!!!!!
The sieve and the sand are symbols and metaphors in the second part of the book. They represent Montag's quest for knowlege, and being incapable of holding onto all that he wants and needs to remember.
He remembers a time in his childhood that he is trying to fill a sieve with sand and of course is unable to do so. The comes to his mind when he is reading the Bible on the train and trying to remember what he reads. Of course, with all the advertisements on the train he is not able to concentrate so he becomes frustrated with the fact that he can't take in and remember all the information that he craves and feels as if he needs.