Symbols are objects, characters, figures, and colors used to represent abstract ideas or concepts.
George and Lennie's Farm
The farm that George constantly describes to Lennie - those few acres of land on which they will grow their own food and tend their own livestock - is one of the most powerful symbols in the book. The other characters and the reader wants to believe in the possibility of the free, idyllic life it promises. Candy is immediately drawn in by the dream, and even the cynical Crooks hopes that Lennie and George will let him live there too. A paradise for men who want to be masters of their own lives, the farm represents the possibility of freedom, self-reliance, and protection from the cruelties of the world.
Lennie's Puppy
Lennie’s puppy is one of several symbols that represent the victory of the strong over the weak. Lennie kills the puppy accidentally, as he has killed many mice before, due to his failure to recognise his own strength. Although no other character can match Lennie’s physical strength, the huge Lennie will soon meet a fate similar to that of his small puppy. Like an innocent animal, Lennie is unaware of the vicious, predatory powers that surround him.
Candy's Dog
In the world Of Mice and Men describes, Candy’s dog represents the fate awaiting anyone who has outlived his or her purpose. Once a fine sheepdog, useful on the ranch, Candy’s mutt is now debilitated by age. Candy’s sentimental attachment to the animal—his plea that Carlson let the dog live for no other reason than that Candy raised it from a puppy—means nothing at all on the ranch. Although Carlson promises to kill the dog painlessly, his insistence that the old animal must die supports a cruel natural law that the strong will dispose of the weak. Candy internalizes this lesson, for he fears that he himself is nearing an age when he will no longer be useful at the ranch, and therefore no longer welcome.
Rabbits
The rabbits represent Lennie's dream and hint at the impossibilty of the dream becoming true. When Lennis begs George to talk about the dream, he begs to hear about the rabbits. The ranch itself and the freedom it represents is George's dream - Lennie simply wants to be able to tend to the rabbits. When George and Lennie first come upon the clearing in the opening of the story, Steinbeck describes the rabbits scattering. This may represent that Lennie's dream will run away from him, too.