Plato's Republic (Unabridged‪)‬

Plato's The Republic is regarded as one of the most significant works in the history of literature. In it, Plato seeks to define justice - what it means to society, to politics, to humankind. He then hopes to draw a conclusion against mass justice and individual justice. He first defines justice via social classes, but then migrates to the idea that personal justice mirrors that of the organized, or governmental, justice. He uses the analogy of the sun, the line, and the cave to draw similarities between the philosopher and his role to play in societal justice. Finally, Plato concludes that justice is justified by the ends and not the means, that is, it provides individual pleasure beyond just "right" and "wrong." 

Considered a great book of all classical literature, Plato's The Republic is a must-listen for those wanting to explore the element of justice more.