Lewis likewise claimed that

[i]f a man will go into a library and spend a few days with the Encyclopedia of Religion and Ethics he will soon discover the massive unanimity of the practical reason of man. From the Babylonian Hymn to Samos, from the Laws of Manu, the Book of the Dead, the Analects [of Confucius], the Stoics, the Platonists, from Australian aborigines and Redskins, he will collect the same triumphantly monotonous denunciations of oppression, murder, treachery and falsehood, the same injunctions of kindness to the aged, the young, and the weak, of almsgiving and impartiality and honesty. He may be a little surprised (I certainly was) to find that precepts of mercy are more frequent than precepts of justice; but he will no longer doubt that there is such a thing as the law of nature. . . . [T]he pretence that we are presented with a mere chaos -- though no outline of universally accepted value shows through -- is simply false and should be contradicted in season and out of season wherever it is met. Far from finding a chaos, we find exactly what we should expect if good is indeed something objective and reason the organ whereby it is apprehended -- that is, a substantial agreement with considerable local differences of emphasis and, perhaps, no one code that includes everything (Christian Reflections, pp. 77-78, emphasis in original).

Lewis noted that what is common to all these concepts is something crucial: "It is the doctrine of objective value, the belief that certain attitudes are really true, and others really false, to the kind of thing the universe is and the kind of things we are. . . . No emotion is, in itself, a judgement; in that sense all emotions and sentiments are illogical. But they can be reasonable or unreasonable as they conform to Reason or fail to conform. The heart never takes the place of the head: but it can, and should obey it" (The Abolition of Man, p. 19).

As such, Lewis firmly rejected the idea that only those who are Christian can understand morality or be moral because the natural law is fundamental to human existence and serves as the basis for human choice. He noted that if only Christians were able to be moral or to understand morality, then there would exist an unworkable dilemma in which no one would be persuaded of being (or ever be able to become) moral who was not already a Christian, and hence no one would ever become Christian. "It is often asserted that the world must return to Christian ethics in order to preserve civilization. Though I am myself a Christian, and even a dogmatic Christian untinged with Modernist reservations and committed to supernaturalism in its full rigour, I find myself quite unable to take my place beside the upholders of [this] view. It is far from my intention to deny that we find in Christian ethics a deepening, an internalization, a few changes of emphasis in the moral code. But only serious ignorance of Jewish and Pagan culture would lead anyone to the conclusion that it is a radically new thing" (Christian Reflections, pp. 44, 46).

Lewis argued that a natural moral law is known to all, and this natural moral code is inescapable; it is the basis for all moral judgments. Its foundational truths such as "caring for others is a good thing," "good should be done and evil avoided," "dying for a righteous cause is a noble thing" -- are understood regardless of experience, just as we know that 2 + 2 = 4.