Final answer:
The figure of speech used in the given sentence is metaphor.
Step-by-step explanation:
The figure of speech used in the given sentence is metaphor. A metaphor is a figure of speech that compares two unlike things by saying that one thing is another. In this case, the sentence compares the act of cashing a check to the acquisition of riches and security. By using the metaphor of cashing a check, the author is emphasizing the idea that freedom and justice are valuable and can be obtained through a specific action.