The sometimes fine line between madness and sanity was nowhere better illustrated than by the “balance of terror” that existed between Nato and the USSR until the collapse of communism. The massive threat each posed to the other ensured the annihilation of both in the event of a nuclear exchange. Labelled Mad - mutual assured destruction - it was arguably the sanest of compromises under circumstances that challenged the very notion of human rationality.

The punning title of Adam Phillips’s remarkable Going Sane hints at a similar overlap between sanity and madness, though more in the personal than the political arena. For Phillips, sanity and its inexactly imagined opposite are found everywhere, bringing varying degrees of benefit or damage to all of us. Life can best be managed, if not improved, only after classifying and modifying feelings and conduct according to whether they are thought sane or not.

Attitudes to parenting and money, for example. To nurture “the realism required for psychic survival (and) a dignified apprehension of limits”, children should be reconciled to the simple but often-avoided fact (avoiding it being a sign of madness) that life doesn’t always work out.

Phillips applies a similar principle to money, noting that relentless earning and spending is at best a distraction, at worst an “insane” self-deception.

Put thus, these and other observations - on sex and adolescence, for instance -might seem trite. What makes this work exceptional is not so much Phillips’s conclusions as how they are reached. Reasoning and references so dense - let alone reflections so aphoristic, allusive and sometimes paradoxical (“Sanity, at its best, becomes a sustained and sustaining madness”) - create a text that, like life itself, resists easy understanding or explanation. Yet it is this very complexity that makes Going Sane irresistible, both as a guide to living and an exploration of the links between behaviour and morality.