Our human nature has one prevailing objective that overrules all and controls all . . . we sin. It is our nature to sin. We sin because we are sinners. We have no choice but to sin during our lifetimes. In the Old Testament law, this nature was captured in two ways: apodictic law and casuistic law.
Casuistic law was the type of law requiring an example or case. For example, if a man builds a house with unsafe supports and it falls on a person, then a casuistic law would cover this case. If there was a law outlining such an incident then the person at fault can be charged. This is a casuistic law because it needs a cause (a man to build a house) in order for it to happen.
This type of law doesn’t cover human nature. It isn’t in every person’s nature to build a house.
However, apodictic law covers those laws which are human nature. The Ten Commandments are such law. It is human nature to kill, so God says, “do not kill.” It is human nature to lie, so God says, “do not lie.” This goes on to cover coveting, idolatry, etc. God does this to show us that our human nature is twisted and sick. That is our nature, wrapped up in one chapter: Exodus 20.