what did gulliver learn from the ghost of different people?

Gulliver learns that Alexander the Great did not die from poison but from excessive drinking.

"Caesar freely confessed to me, “that the greatest actions of his own life were not equal, by many degrees, to the glory of taking it away.”

"I had the honour to have much conversation with Brutus; and was told, “that his ancestor Junius, Socrates, Epaminondas, Cato the younger, Sir Thomas More, and himself were perpetually together:”