Who is Sacco and Vanzetti from Jailbird and what is their importance?

These characters never actually appear in the book, but are referred to several times. They, like a number of other secondary characters, are actual historical individuals, Italian immigrant workers falsely arrested, tried, and executed for murder. They are portrayed throughout the book as icons of the wronged, idealized and victimized metaphoric examples of how the less advantaged can be destroyed by capitalism.