Which question does the Blackfoot story try to answer

What is the central idea in this advice from branch rickey to jackie robinson?  

The greatest gift the sumerians gave the world was the invention of writing. the sumerians were a wealthy people. they needed some way to keep track of what they owned. they began drawing pictures. they used a reed as a pen. they drew on soft pieces of clay. the soft clay was then dried in the sun. the tablet became a permanent record. later, the sumerian drawings changed into wedge-shaped symbols. this kind of writing is called cuneiform. by putting symbols together, the sumerians could write entire sentences.

Mr. underwood's editorial defending tom robinson is surprising because he's described as not wanting to be near negroes it's a dangerous stance to take at that time he had been neutral during the trial he wasn't in the courtroom