Final answer:
It is true that Socrates, as depicted in Plato's The Republic, insists that a well-balanced person with a sense of justice is the only one who can achieve happiness. This idea is rooted in Plato's theory of justice, which advocates for each part of society to function harmoniously in their designated roles, especially the ruling class or 'guardians'. Harm to one's character is considered to be worse than death, emphasizing the importance of justice to one's soul.
Step-by-step explanation:
In Plato's dialogue The Republic, it is true that Socrates insists that only a well-balanced person with a sense of justice can be happy. The text explores various aspects of what constitutes a just society and the nature of justice itself. Through Socratic dialectic, Plato asserts that a just individual operates in a role suited to their nature and does not intrude upon the roles of others. This specialization and harmony amongst societal roles foster a state of justice.
Plato's theory of justice is centered on the idea that society should function harmoniously with each part or class performing its designated role - the producers, the auxiliaries (soldiers), and the guardians (rulers). It’s in this context that the role of guardians becomes pivotal, as they are required to embody the virtues of wisdom and courage and to place the interests of the society above their own. In creating the allegory of the just city, Plato demonstrates that a society based on justice is the key to the happiness of its citizens.
Socrates believed that harm to one's character was more significant than even death because death affects only the body, whereas harm to one's character affects the soul, which he deemed to be more essential. It's from this belief that he derives the importance of justice, as it nurtures and protects the character of the citizens and thereby contributes to their happiness.