Final answer:
Martin Luther King Jr.'s 'palace of justice' metaphor symbolizes the achievement of civil and human rights in a peaceful and equitable manner.
Step-by-step explanation:
In the excerpt from Martin Luther King Jr.'s "I Have a Dream" speech, the 'palace of justice' metaphor represents the ideal state of civil and human rights that African Americans aspire to reach. The metaphorical palace signifies a place where equality prevails and racial injustice is no longer present. In this passage, King urges his audience to pursue justice through peaceful means, without succumbing to bitterness or hatred, despite the challenges and injustices they face.