InCognito

The problem assumes the greatest importance when we consider that we are probably only at the threshold of an age in which the technological possibilities of mind control are likely to grow rapidly and what may appear at first as innocuous or beneficial powers over the personality of the individual will be at the disposal of government. The greatest threats to human freedom probably still lie in the future. The day may not be far off when authority, by adding appropriate drugs to our water supply or by some other similar device, will be able to elate or depress, stimulate or paralyze, the minds of whole populations for its own purposes. If bills of rights are to remain in any way meaningful, it must be recognized early that their intention was certainly to protect the individual against all vital infringements of his liberty and that therefore they must be presumed to contain a general clause protecting against government’s interference those immunities which individuals in fact have enjoyed in the past. (The Constitution of Liberty, 2011 [1960], 325)

 He also includes a footnote concerning Aldous Huxley's Brave New World.

For a none too pessimistic account of the horrors that may be in store for us see Aldous Huxley, Brave New World: A Novel ... and Brave New World Revisited... and, even more alarming, because not intended as a warning but expounding a 'scientific' ideal, Burrhus Frederic Skinner, Walden Two.

My guess is that, in some manner, Hayek had in mind the eugenics movement that had peaked shortly before he published The Constitution of Liberty. I'd be delighted if any readers could share their insight.