In June 1974, Oliver Sacks wrote to Bob Rodman, a psychiatrist who had been a close friend since they were both medical residents at UCLA. Rodman’s wife, Maria – only 38 years old – had been diagnosed with a mysterious illness that would eventually prove fatal; Rodman wrote to Sacks of his shock, his despair; suicide, he wrote was a “luxury” since the couple had two young daughters. Sacks’s response is, like so much in this extraordinary volume, a model of honest compassion which powerfully acknowledges the pain and challenge of grief.

“I wish I had not been so blind before,” he writes, apologising for a delay in answering. “I did see that you were in the throes of crisis, but I failed to see the real and agonising events behind it.” He offers his own experience, not as distraction, but as means of connection: “I know very well those forces which shut one up and in, which confine one in an extra hell , when one most needs to reach out towards others, towards one another.

” But it wasn’t only to his close friends that he offered such warmth, and the kind of advice that considered the recipient’s whole circumstance; three years later he writes to a woman identified only as “a correspondent” who has contacted him as she struggles to care for a husband with Alzheimer’s. She wrote to him asking if he knew of a cure; he says plainly that there is none. But, he says, the task before her must not be at ultimate cost.

“I hope you do not misunderstand.