What was one root cause for slavery?

Read the excerpt below and answer the question. obierika was a man who thought about things. when the will of the goddess had been done, he sat down in his obi and mourned his friend’s calamity. why should a man suffer so grievously for an offense he had committed inadvertently? (p. 125) based on the context clues, the best definition for the word “calamity” in the excerpt above is disaster sadness luck indifference