… is from pages 442-443 of Hayek’s 1976 lecture “Socialism and Science,” as this lecture appears as Chapter 29 of Essays on Liberalism and the Economy (2022), which is volume 18 (expertly edited by Paul Lewis) of The Collected Works of F.A. Hayek:
In a society whose wealth rests upon prompt adaptation to constantly changing circumstances, the individual can be left free to choose the directions of his efforts only if rewards fluctuate with the value of the services he can contribute to the society’s common pool of resources. If his income is politically determined, he loses not merely the incentive but also the possibility of deciding what he ought to do in the general interest. And if he cannot know himself what he must do to make his services valuable to his fellows, he must be commanded to do what is required.