I believe the answer is:
<span>to reveal past contributions of civilizations
to connect the past to the present
to recognize patterns
By knowing all the things above, future society could learn from the past society and started to make efforts to prevent the bad decision that made in the past from reoccurring. This would help the society to continue developing without facing unnecessary setbacks.</span>
Lee Harvey Oswald was responsible for killing/shooting John F. Kennedy.
He went to Texas to raise more Democratic Party presidential campaign funds, wanted to begin his little 'quest' for reelection, and because the Kennedy-Johnson ticket just barely won Texas.
<span>The influx of a large number of foreign labor in need of jobs, representation, assistance and recognition. These immigrants could be pooled to provide leverage at the voting booth for the promised patronage of the political machines like Tammany Hall</span>