Lewis understood, with prophetic lucidity, that our ills today are largely the result of our ongoing attempt to escape from our own nature.
Such is the theme of his first chapter, "Men without Chests." In it, Lewis pillories a lamentable book (typical of his time and ours) that attempts to indoctrinate mere schoolchildren with moral and intellectual relativism. The authors, whom he calls Gaius and Titius (in reality, Alec King and Martin Ketley), declare matter-of-factly that words don't have any real connection to things, but are mere descriptions of our subjective feelings. "This confusion is continually present in language as we use it," they assert. "We appear to be saying something very important about something: and actually we are only saying something about our own feelings."
For Lewis, these were fighting words, because they were words designed to usher in peace at any cost, even at the cost of truth, words designed to make chestless men who believed in nothing and hence would fight over nothing.
Here Lewis brilliantly ties together two modern trends: the emasculation of society and widespread intellectual and moral relativism. Both of these trends have one aim: to make men peaceful by removing the great sources of war (at least as some see things), the belief that there is truth, and that the truth is worth fighting for. Chestless men, men whose fighting spirit has been entirely quashed by relativism and the belief that manliness itself is one of the great sources of the world's evil, are at least peaceful men. And for those who desire peace at any cost, the deformation of men and the destruction of the natural human desire for truth is a small price to pay. It is no accident that King and Ketley's book was written between the two hideously destructive World Wars.
According to this view, we must, for our own survival and peaceful co-existence, escape from our own nature. Maleness must be left behind; it must have no place in our brave new world. Passionate truth-seeking is likewise a thing of our bloody past; it must have no place in our schools, our public discourse, our media.
What such a view fails to understand, Lewis argues, is the greater cost of the deformation of our nature. Chestless men are stunted men, men whose desires never rise above the belly and the groin, men who are willing slaves to the soft despotism of the state that provides their ever more degraded pleasures. The defining political and social goal becomes the provision of bread and circus, food and mindless entertainment, so that the great masses will be quiet cattle.
Men who do not care about the truth may be peaceful men, but they are malleable clay in the hands of those in political control who—since they are moral and intellectual relativists too—don't mind remolding human beings in their own particular image to suit their own particular plans. The abolition of men and manhood leads, Lewis argues, to the abolition of man the species, to the remaking, remolding of human nature in whatever way pleases those in power, both through oppressive indoctrination/education and actual technological manipulation.