From Chapter 4, Freedom, Reason, and Tradition, of his Constitution of Liberty:
“The argument for liberty, in the last resort, is indeed an argument for principles and against expediency in collective action, which, as we shall see, is equivalent to saying that only the judge and not the administrator may order coercion. When one of the intellectual leaders of nineteenth-century liberalism, Benjamin Constant, described liberalism as the système de principes, he pointed to the heart of the matter. Not only is liberty a system under which all government action is guided by principles, but it is an ideal that will not be preserved unless it is itself accepted as an overriding principle governing all particular acts of legislation. Where no such fundamental rule is stubbornly adhered to as an ultimate ideal about which there must be no compromise for the sake of material advantages—as an ideal which, even though it may have to be temporarily infringed during a passing emergency, must form the basis of all permanent arrangements—freedom is almost certain to be destroyed by piecemeal encroachments. For in each particular instance it will be possible to promise concrete and tangible advantages as the result of a curtailment of freedom, while the benefits sacrificed will in their nature always be unknown and uncertain. If freedom were not treated as the supreme principle, the fact that the promises which a free society has to offer can always be only chances and not certainties, only opportunities and not definite gifts to particular individuals, would inevitably prove a fatal weakness and lead to its slow erosion.”
