This set of three lectures by C.S. Lewis begins with "Men Without Chests". This lecture or essay examines problems that he sees in a book for use in teaching English. In it the authors regularly debunk value statements as being statements about "mere" emotions. Lewis proceeds to demonstrate that some value statements are not merely statements of emotion. Some things are properly described as repulsive and others are properly described as noble. This act of debunking makes it harder for the students later because trained emotions, metaphorically seated in the heart or chest, are necessary for people to do the right thing. Hence the title "Men Without Chests", that is men who haven't got the trained emotions and are therefore made less able to behave morally.
The second lecture "The Way" takes the book that triggered the first lecture and generalizes to a philosophy of the time. Specifically, Lewis attacks the idea that morality can be based on something that admits of proof, and the idea that such a proof is required before a person ought to believe in an objective morality without proof. He demonstrates the problem with social utility and instincts, two things that some authors of the time used in their attempts to build new moral frameworks. Both run into the problem of moving from an "is" to an "ought". He then goes on to point out a difficulty in "seeing through" things. The point of "seeing through" is to see something on the other side. If you see through everything then everything is transparent and you are effectively blind. This difficulty serves as the justification of accepting the claim that people should accept the existence of an objective morality. Another way of making the claim: everyone acts like there is an objective morality; therefore they must believe that such exists.
The third and final lecture "The Abolition of Man" moves on to the broader interaction between Science and morality. It largely consists of an examination of the claim "Man is conquering Nature". Lewis uses radio, airplanes, and contraception as examples in his demonstration that the "conquest" is a matter of some people getting more power to impact the lives of other people. In the case of contraception it is power by people of "this" generation over those that would otherwise be in future generations. This concern moves into education and raises the problem of individuals that free themselves from the "Tao", the term used in these essays for objective morality, as humanity gains the knowledge to use unfailing conditioning to control and shape students. This interaction leads to an argument regarding the necessity of objective morality by scientists and those pursuing science.
The first essay is mostly of interest in education, particularly textbook reviews. After all English textbooks should teach the students how to write, not an amoral philosophy. The third is mostly irrelevant. After all science has yet to provide any reliable way of shaping students to be precisely what the powers that be want, and it seems unlikely to do so in the near future or even the not so near future. The second is of greater interest as it fits into the ongoing struggle over the foundation of ethics.
All in all this, along with "Mere Christianity" and "A Grief Observed", is one of C.S. Lewis' books that everyone ought to read at some point. For its lucidity, for the structure of his arguments, and for the conclusions it is a book well worth reading.