The Republic: A guide to an analogous concept of One's meaning of Justice

For what reason do men act fairly? Is this is because they dread cultural discipline? Is it accurate to say that they are shuddering before ideas of heavenly revenge? Do the more grounded components of society alarm the feeble into accommodation for the sake of law? Or on the other hand, do men act fairly because it is useful for them to do as such? Is equity, paying little heed to its prizes and disciplines, something worth being thankful for all by itself? How would we characterize equity...