Human heart is so mysterious that even God cannot understand what the human heart thinks about. That was why God inspired many scholars to write down His will how human should behave. It is the Bible today.
In the modern society today, no one even in the university will study to ascertain whether human heart is kind or vile.
But, more than two thousand years ago, in ancient China, a hot discussion was carried out between scholars. One group was in favour of good heart in human and another group was against, saying that human heart was vile basically.
The head of the favoring good group was Mencius who made an example by saying that a bandit, whose job was to kill people for his robbery, was walking one day in the street and saw a baby boy climbed toward the edge of a well. In few inches further, the baby boy would fall into the well which was twenty feet deep down with water. The bandit, without hesitation, jumped to the side of the well and the baby was saved.
The leader of another group was Shang Yang who insisted that human heart was vile. That is why we need law to protect good people from evil ones. If human heart is good, law will not be necessary to govern people. Therefore, it is a subject for us to ponder.