When he was a boy, Mark Solms obsessed over big existential questions. What happens when I die? What makes me who I am? He went on to study neuroscience but soon discovered that neuropsychology had no patience for such open-ended questions about the psyche. So Solms did something unheard of for a budding scientist. He reclaimed Freud as a founding father of neuroscience and launched a new field, neuropsychoanalysis.

Solms had one other obstacle in his path. Born in Namibia, where his father worked for a South African diamond mining company, he grew up under apartheid in South Africa. Solms later worked at a hospital in Soweto, where a military occupation tried to clamp down on protesters. “Once you reach the end of your studies, you’re required to join the very same army whose victims I was looking after,” he told me. “That was emotionally impossible.” So he fled to England, where he trained as a psychoanalyst, and didn’t move back to South Africa until apartheid was dismantled.

If my brain were damaged, would I be a different person? Where would the original version of me go?

Solms has spent decades working to reconcile brain science with the study of lived experience. Now, he presents his own theory of consciousness in a new book, The Hidden Spring. Solms believes neuropsychology has been looking for consciousness in the wrong place. “Since the cerebral cortex is the seat of intelligence, almost everybody thinks that it is also the seat of consciousness,” Solms writes. “I disagree; consciousness is far more primitive than that. It arises from a part of the brain that humans share with fishes. This is the ‘hidden spring’ of the title.” The book is a deep dive into modern neuroscience, peppered with surprising explanations for how we think, dream, remember, and perceive.

I reached Solms in Cape Town, South Africa, where he’s stayed during the COVID-19 lockdown. We talked about the brain-mind problem, the biases of neuropsychology and how a family