It’s easy to write off the hippie movement as essentially unserious. Most of them were young; few of them were sober; they said things like “groovy” and “far out.” And in part, the hippies were animated by psychic impulses that weren’t new: the youthful rejection of the apparent mundanity of adulthood, and good old hedonism.

But lurking beneath the shallow motifs – flowers in the hair, acid on the tongue – was a serious philosophical protest. “At the deepest level,” writes W. J. Rorabaugh, in one of the few good histories of the movement, the hippies expressed “a crisis of belief.”

What the hippies were unable or unwilling to believe in was pretty much every norm of mainstream culture. Like their philosophical antecedents – the Transcendentalists, the Bohemians, the Beats – the hippies regarded modern life as a soulless, runaway machine, a vast conglomeration of bureaucracies that rendered people shrunken, sexless, and mean. To the hippies, each of society’s ills was symptom, not disease. The soul death of the cubicle farm; the heat death of the planet; slaughter in Vietnam; slaughter in the factory farms – these were all the result of a society which had prioritised all the wrong elements of the human spirit. Instead of love, there was ego. Instead of creativity, conformity. Instead of joy, shame.