There is no limit to our liberty of thought. Our imagination, too, is as free of all constraint as the wind blowing over the desert sand. Our intelligence can follow logical principles or ignore them, just as it pleases. Everyone has the privilege of being illogical when he wants to. He is also privileged to erect logical constructions which are based on concrete reality, such as Euclidean geometry, or others which have no connection with it, such as the geometry of Riemann. Equally, there is no barrier to the expression of our feelings. We are free to give ourselves up to jealousy, rapacity, pride, intemperance, lust and selfishness; to follow all our impulses and indulge all our appetities. We are almost as free in our actions as in our thoughts and feelings. Man is allowed to behave as he wishes; the vast vista of the possible lies open before him.

Our liberty of thought and action is bounded only by the consequences of those thoughts and deeds. The field of the possible is divided into two sectors by an invisible and immutable frontier. In one sector, our freedom can be safely exercised; in the other it sooner or later brings catastrophe. The frontier is fixed forever by the nature of things; by the structure of ourselves and of the cosmos. Our ancestors possessed a traditional wisdom, a kind of intuition of the dangerous regions, which we now despise. Because we ignore the barrier between the permissible and the forbidden, we cannot use our freedom with impunity.

The aim of the science of living is precisely to demarcate this frontier for us, to show us how to keep on the safe side of it, to teach us, in fact, how to use our freedom in a rational way. It is easy to know what margin of safety is left us by the laws of chemistry and physics. A child soon learns that it cannot walk on a pond like a water beetle or support itself in the air like a butterfly. It learns in good time that fire burns. But it will never realize of its own accord that to eat nothing but meat and cakes is just as dangerous. Many physiological laws are not merely quite unknown to the general public but very imperfectly known to scientists. Most people have only a rudimentary knowledge of themselves. Their notions of hygiene, for example, are extremely sketchy. Napoleon was a victim of this ignorance. If Gam-betta was an old man at forty-two, this was undoubtedly due to his having deliberately underfed himself in his youth. The moderns do not realize that education and sociology also have laws, less clearly defined but as sacrosanct as those of physics. They still allow themselves to be guided by philosophers and reformers. They bow to Jean-Jacques Rousseau or John Dewey in the case of education; to Adam Smith, Jeremy Bentham or Karl Marx in the case of sociology.

As the laws of life usually only punish their transgressors after many generations, we have not learned to submit to them as we submit to physical laws like the law of gravity. Modern man is the victim of the tragic conflict between natural law and human liberty. Liberty, like dynamite, is an efficacious but dangerous tool. We have to learn to handle it, and to handle it properly demands intelligence and will. The frontier between the permissible and the forbidden is, as we know, invisible. Instead of wandering at will over the vast plain, we must keep to the track. And this track is narrow, rough and ill-defined. We must, then, voluntarily restrict our freedom if we are to succeed in life.

This opposition between freedom and the natural laws makes asceticism imperative. To avoid disaster to ourselves and our descendants, we must resist many of our impulses, tastes and desires. Sacrifice is a law of life. For a woman, to have children entails an interminable series of sacrifices. To become an athlete, an artist or a scientist involves hard training. Health, strength and longevity can only be attained through the refusal to gratify appetites. Our era began under the very sign of sacrifice, yet sacrifice is not a virtue reserved for saints and heroes. It is a specific need of human life. This need became apparent when liberty took the place of the automatism of instinct for our forebears. Every time man has used the whole of his liberty, he has infringed the natural laws and been severely punished.

Neither philosophers nor theologians should attempt to construct man according to their particular doctrines, whatever those doctrines may be, for man's horizon is always too narrow. It is sheer pride to believe oneself capable of correcting nature, for nature is the work of God. Man should be what his inherited potentialities permit him to be. He must develop the tendencies we humbly attempt to decipher in his body and soul. We have the power to mold youth almost exactly to our own desired pattern, for living matter is infinitely plastic. With good techniques we could construct the man we wished but this product of our doctrines would not be viable. Like ourselves, the creature would sooner or later be engulfed in folly, corruption and chaos. To command nature, we must obey her. The price of success in our personal, social and racial life is humble submission to the immutable nature of things.