Cohen lets us know early on that his work is part history (exploring Freud’s drug use) and part polemic on the current place of drugs within society. Perhaps with this in mind he warns us that we ‘are now entering a war zone’.

The central story begins in the conversational manner of a late-night bar, developing some drama through damaging letters between Freud and Wilhelm Fleiss, which Freud managed to suppress during his lifetime through the help of a princess (Marie Bonaparte) rather than a super injunction. The ultimate survival of the letters, owing to the princess/patient’s refusal of her analyst’s wish that she destroy them, helps Cohen depict Freud’s ambitious, and sometimes disastrous, experiments with cocaine during a time of more general European enthusiasm for this drug (Merck’s European import increased from 58 000 leaves in 1881 to 18 396 000 in 1885). Despite his energetic pursuit of success, Freud overlooked the significance of cocaine’s anaesthetic properties and while his colleague, Karl Koller, blazed a trail for ophthalmic and dental surgery with the use of cocaine-anaesthetic across two continents, Freud pursued the ultimately less rewarding path of ‘naso-sexual neuroses’. The Fleiss letters provide testimony of the dreadful injury inflicted on Freud’s ‘neurotic’ patient Emma Eckstein along with Freud’s continued heavy cocaine use during his eventual breakthrough with the published, edited analysis of his dreams.

But Cohen also shows us Freud as part of an important tradition of serious, introspective experiment in psychotropic drugs, continued here through Albert Hofmann (the bicycling, Swiss discoverer of lysergic acid diethylamide) and Aldous Huxley’s wonderful account of his Californian mescaline experience. Within late capitalism this tradition of exploration has lapsed and the search for transcendence through psychedelics has given way to a search for the firmer, clearer ego boundaries of a growing range of ‘neuro-enhancers’ that promise to help us work harder rather than enabling us to ‘open the doors of experience’.

Although Cohen often finds his target, there is a good deal of collateral damage, particularly when examining professional involvement in psychotropic drugs. Psychiatrists challenging the very debatable findings of an Irving Kirsch meta-analysis are dismissed as a ‘pro-pharma shrink duo’ (the biographer E. M. Thornton fares little better as an ‘outraged spinster-librarian’). These ad hominem attacks appear as shorthand in Cohen’s polemic but do not help establish its credibility, which is further undermined by a poor understanding of basic medical science – as when we are told that a Glasgow Coma Scale of 15 indicates ‘at least minor brain damage’.

An engaging history – as long as you tread carefully between the landmines.