The title of John Steinbeck's Of Mice and Men is an allusion to "To a Mouse," a poem written by Robert Burns, who lived during the 18th Century. In this poem about a farmer who turned up a mouse's burrow while ploughing Burns writes, "The best laid schemes of mice and men, / Go oft astray, / And leave us nought but grief and pain, / To rend our day."
There have been many references to this poem in popular culture. The poem's comparison between mice and men is apt for this novel because people like George and Lennie could have their lives turned upside down by the metaphorical plough and receive only passing sympathy.
Another reason this title is apt is that, in the poem, the mouse believed its winter home would be the best way to survive the cold whether. This plan went "astray." In Of Mice and Men, each character presented in the book has some type of dream he or she feels destined to reach. For George and Lennie, it's owning a ranch where Lennie can take care of the bunnies. Both Crooks and Candy want to join the guys on that ranch. For Curley's wife, it is going to be a movie star. But for every character, there is a dashed dream. Their "best laid schemes" went "astray."