In Ray Bradbury's Fahrenheit 451, Montag relates the story of how, as a child, an unkind cousin told him that if he could fill a sieve he would receive a dime. Try as he might, he was unable to do so because the sand passed through the holes in the sieve. In essence, he was trying to do the impossible and was greatly frustrated. After a time he realized that no other outcome could have been achieved.
Montag is presented with the task set before him by Clarisse—who planted the seeds of attentiveness in Montag's mind as he has lived among others of his society that have been "pounded into submission." Original thought has been strongly discouraged; books are banned. Seeing the world as if through new eyes, Montag is no longer capable of passing by people and things around him without seeing them—as he had before. Now he feels driven to catalog these perceptions in his brain and try to comprehend the significance of each.
Montag battles desperately to make sense of the words in the Bible that he holds in his hand. It has been said, and Faber has confirmed, that there are no more Bibles in existence. Montag believes he may be holding the only one left in his part of the world. He believes that he will ultimately have to turn the book over to his boss Beatty, but until then he must read and remember every word. However, like filling a sieve with sand, it is impossible. One rease is that as he reads, the piped-in music and commercials from the speakers that are used to promote mindlessness are thumping at his brain even as he tries to memorize a simple verse.
...he remembered the terrible logic of that sieve, and he looked down and saw that he was carrying the Bible open. There were people in the suction train but he held the book in his hands and the silly thought came to him, if you read fast and read all, maybe some of the sand will stay in the sieve.
It is in this way that the motif of sand in a sieve is illustrated, as the words he reads seem to fall on the ground before him rather than taking root in his mind...
...he read and the words fell through...[but he thought] no phrase must escape me, each line must be memorized. I will myself to do it.