Who knew that our favourite avuncular neurologist used to be the biggest dopehead in mid-1960s California?
Discreetly tucked into this beguiling package of case histories about every variety of hallucination - phantom limbs to ghosts and voices - is Sacks's report on his drug use while a young doctor.
The voracious experimenter even mixed his own cocktail, a "pharmacologic launchpad".
What brought him back to earth? Bad trips, yes, but also the discovery that sharing his clinical expertise in words delivered the best high.