Book One is all about different aspects of the law: the law of human nature, the reality of the law, some objections to the law, what lies behind the law, and how it all plays into the reaction and uneasiness of humanity. After addressing these aspects, Lewis goes on to write Book Two, which includes more details on these topics from a Christian point of view.
The Law of Human Nature- This is the idea that just as all bodies are governed by the law of gravitation, and organisms by biological laws, so humans also have a law that is peculiar to all of them-us-that contains a difference than any biological law, that a body could choose to obey or disobey the Law of Human Nature. Essentially, it can be thought of as the Law of Right and Wrong. An objection to this may be that morality is different in varying societies or civilizations, and although there have been differences between moralities, these have never amounted to anything like a total difference. Lewis uses the example that nobody has a morality so different that they would say a man should be proud if he double-crosses all the people who had been kindest to him, or where a person is thought admirable if he runs away in battle. An example to prove this too is this: the minute someone breaks a promise to somebody else and the second person says, 'That's not fair', that man is judging by some higher standard. If the Law of Human Nature does not exist, then what is the difference between fair and unfair? Humanity is forced to believe in a real right and wrong. What's interesting is that as humans, though we have an idea that we ought to act a certain way, do not follow this standard. We are constantly breaking the Law of Nature.
Here Lewis goes on to address points of objection, such as The Moral Law, inspiration by social convention, and education affecting morality but it is rather long and lengthy, so I suggest you simply buy the book and read it for yourself.
The Reality of the Law- The Law of Gravitation (for example) tells you what stones do if you drop them and differs from the special law that governs humanity, because the Law of Human Nature tells you what human beings ought to do and not do, something else is coming into the picture that is above and beyond the actual facts. When it gets down to it, Lewis concludes that men ought to be unselfish and fair, an idea that humanity cannot rid of but is consistent in advocating. This is indeed a thought that is pressing on man. Where can this idea come from? We have said already it is an idea that is outside the biological laws we know, but for some reason humanity holds to the trueness of the concept anyway, knowing it is right even when man acts in the wrong. Therefore, this rule of right and wrong is a very real thing and is something that is above and beyond the ordinary facts of men's behavior. As Lewis says, 'It is a law that none of us made'.
What Lies Behind the Law- Now Lewis addresses different views on how the universe came to be and what it all really means. Although there are multiple views, Lewis presents two that seem to be the main ones humanity agrees with. The first is the materialist view, which is to say that matter and space happen to exist with no lasting or real purpose but all simply a fluke creatures like ourselves came to exist. The second view is the religious view, which says there is some sort of mind behind the universe that has purposes and preferences that affect all of humankind. Note this: science can not determine the purpose behind humanity. Science observes and watches how things behave. I am not saying anything against science and am actually fascinated by what God allows us to know and understand through the subject, but it is true that why anything comes to be there at all, and whether there is something behind the things science observes-something above and beyond the limits of testing-is not a scientific question. The meaning of the universe is very much bigger than science and man. Is it then a hopeless question to ask at all? Lewis says no, for there is one part of life that we do not only observe but actually experience: man. We are men (and women!). We have inside information, and because of this are able to say that man has a moral law which we know ought to be obeyed but often isn't, and that law is not of us but is still pressing on us. Does this not arouse suspicion? It would seem that man must say there is a Power behind it all, sending the law and acting as a Director or Guide. Even this does not lead to concluding in the Christian God, but rather it is acknowledging there is Something directing the universe and man.
We Have Cause to be Uneasy- Most would look at this and view it as biased and based on already existing ideas, but this is not so. All that is presented here is what Lewis has observed independently as a man. What he finds-and what those following and agreeing find-is quite shocking: the universe that has Something behind it and then the Law of Human Nature that this Something has sent to man. Why is this terrifying? It seems that there is an absolute goodness, and because humanity is fallen, it must hate what humans do. This idea of sin is presented here and can be defined by breaking the Law of Human Nature, which is to stray from an absolute goodness. Humanity is in a fix. We make ourselves enemies to this goodness every day. From here Lewis states, 'Christianity simply doesn't make sense until you have faced the sort of facts I have been describing. Christianity tells people to repent and promises them forgiveness. It therefore has nothing (as far as I know) to say to people who do not know they have done anything to repent of and who do not feel that they need forgiveness. It is after you have realized that there is a real Moral Law, and a power behind the law, and that you have broken the law and put yourself wrong with that Power, that Christianity begins to talk'. Humanity must acknowledge the idea of sin before Christianity works. When you know you are sick you will listen to the doctor.
It is here that Book One ends and Lewis leaves the reader to ponder these ideas presented about the universe and the purpose behind it all. In Book Two he writes about conceptions of God from a Christian point of view as well as different aspects of morality.
Lewis reminds us of this bit of enlightenment, summarized in my own words. If you seek truth, you may find comfort in the end. If you seek comfort, you may not get truth or comfort but simply wishful thinking which leads to despair on somebody's account, usually your own. When it comes to religion, we must set aside wishful thinking and soft soap. We must acknowledge the truth that is pressing on us every second.
