A journey to the core of our being

Robert Macfarlane is on a mission to get us to 'see more deeply'. His latest book is described as 'a time-travelling journey into wonder, fear and the worlds beneath our feet'. A suitably vast exploration of the subterrane as it exists in myth, memory and place, Underland has psychological roots creeping throughout. While it may not be immediately obvious what treasures an audience of psychologists can mine from beneath our feet, Macfarlane writes that 'What I thought would be my least human book has become, to my surprise, my most communal'. There are indeed nuggets buried throughout – strata of individual, relational and societal insight.

It's a dark, deep book; Macfarlane has 'rarely felt as far from the human realm as when only ten yards below it', and he must confront the symbolism of 'what cannot openly be said or seen': loss, grief, the mind's obscured depths, and what Elaine Scarry calls the 'deep subterranean fact' of physical pain. Language can shape our thoughts and behaviour, and in many of the metaphors we live by, height is celebrated but depth is despised. To be 'uplifted' is preferable to being 'depressed'; 'catastrophe' literally means a 'downwards turn', 'cataclysm' a 'downwards violence'. Macfarlane's journeys into darkness – descents made in search of knowledge, to understand – have Freudian echoes of 'the starless rivers of the id that rush beneath the sunlit uplands of the conscious mind, here and there surging powerfully up'.

But importantly Macfarlane is not alone on these adventures… he journeys jovially with 'mappers, really, of networks of mutual relation, endeavouring to stitch their thinking into unfamiliar scales of being, seeking not the scattered jewels of personal epiphany but rather to enlarge the possible means by which people might move and think together across landscapes, in responsible knowledge of deep past, deep future and the inhuman earth'. Fostering that deep time awareness 'runs against the mind's grain'. Macfarlane quotes fellow writer Simon McBurney's view that in our minute splicing of our lives into milliseconds, we live separated from everything that surrounds us.

We need, Macfarlane argues, 'a new language altogether', the soil of grammar and syntax to reshape the way we relate to each other and to the living world. We exist in an 'epoch of loss – of species, places and people – for which we are seeking a language of grief and, even harder to find, a language of hope'. We can look to 'forest wisdom' to appreciate the 'gradual growing-towards and subterranean intertwining' of a long love; fungi can challenge our sense of what is whole and singular, what defines an organism, what descent or inheritance means. Our lives are 'an assembly of entanglements of which we are messily part'. We can and should be 'holobionts' – collaborative compound organisms. Here, Macfarlane admits, he is 'presenting as revelation what indigenous societies regard as self-evident'.

In Macfarlane's hands, the underland is a place where people might slip into different identities, assume new ways of being and relating, 'become fluid and wild in ways that are constrained on the surface'. Broadly speaking, wealth levitates and poverty sinks, and at its more political fringes, urban exploration becomes a radical act of disobedience and liberation: 'a protest against state constraints on freedom within the city'.

We meet 'cataphiles' – lovers of the below, boosted by the arrival of the internet. There are awe-inspiring sections on modern discoveries of ancient cave paintings, heartbreaking passages on the pits of war, and reminders of the power of myth around journeys into the underworld (with the Thai cave rescue as a modern example). And there are take-home messages for scientists too. Merlin Sheldrake (son of Rupert… Google him) muses on writing the 'dark twin' for each scientific paper – 'its underground mirror piece – the true story of how the data for that cool, clean, hypothesis-evidence-proof paper actually got acquired… the frothy, mad network that underlies and interconnects all scientific knowledge – but about which we so rarely say anything'. They discuss how different metaphors of the 'wood' wide web – such as 'free-market' or 'socialist' – drive the scholarship. 'Discourse choice forcefully shapes research directions.'

The spores of this book will continue to spread through my mind. It has inspired a future special issue, and I would love to unearth the social scientists advising the Waste Isolation Pilot Project in New Mexico: 'an atomic priesthood charged with conveying warnings across generations in the form of folklore and myth'. This brings me to the stunning cover of the book: Stanley Donwood's 'Nether', which the artist has described as 'the light of a nuclear blast that has just detonated. When you look at "Nether", you've got about 0.001 of a second of life remaining, before the flesh is melted from your bones.' For Macfarlane this made it perfect for the book: 'Lustrous and lethal, fatal and beautiful, the image beckons the viewer's eye on and down into the underworld. As such, it could hardly be truer to the preoccupations of Underland. For the underland is where we have long placed both what we fear and wish to dispose of, and what we love and wish to preserve.'

Macfarlane began his writing in the mountains, and says he has now 'completed a journey downwards to the darkness at the core of our earth and our imaginations'. Where will he take us next?

- Underland: A Deep Time Journey is published by Penguin on 2 May. See also the editor's 2015 review of Landmarks.

The book has inspired a whole special issue of The Psychologist, loosely themed around the word 'Under', which is scheduled for later this year. There may still be an opportunity to contribute: email [email protected]