My late sister Lucy introduced me to Oliver Sacks back in the late 1980s. Not literally. She didn’t grab me by the sleeve, pull me over at a cocktail party and say: “Hey, Ame, this is Dr. Sacks,” introducing me to the broad, bald Brit who spent his career spelunking and explaining the deepest recesses of the brain. No, Lucy simply called me up one day and announced, “‘The Man Who Mistook His Wife For a Hat’ — you need to read it.”

I read it. And almost everything else he ever published. After Lucy took her own life in 1992, Sacks became, for me, both an invisible thread connecting me to my sister and a way to understand her better — a way to process all that had happened to her, all the temporal-lobe dysfunction and unremitting suicidality that resulted from it. Reading his accounts of brains and brokenness, I felt closer to my sister, more grateful to her, more awed by her strength and stick-to-it-ive-ness in staying alive as long as she did. I learned about the plasticity of the brain, the strangeness of it. I learned about resilience and fortitude and love. All of that was in his books. All of that illuminated his writing and, as I read it, my own eccentric and rattled brain.

Lucy loved him. So did I. We loved him because he treated people like her — people with serious and mysterious neurological woes — with profound comprehension and compassion, never discounting their humanity for the sake of science, never forgetting that the colorblind artist or the autistic anthropologist or the locked-in Parkinson’s patient had joys, depths, yearnings that fell outside the order and disorders of neurology. Instead, the exactitude of his science informed every case study with an exquisite, clear-eyed pathos. His patients weren’t less human because of their problems. They were more human, more realized and whole.

I read a ton of Sacks after Lucy died, cranking through his best-sellers as well as his less-read works — “Hearing Voices,” “Uncle Tungsten.” I returned to him again in late 2011, when, exhausted by my husband’s six-month descent into insomnia, anxiety, depression and suicide, I gave up on easy explanations — there bloody hell weren’t any — and returned to the voice that had always described our oddball human brains with a reverence, a poetry, that saw beyond the broken bits and found creativity, personality and a fabulous, fertile quirk.

I learned from Oliver Sacks that no brain is a simple thing, that no life is easy. But what beauty lies in them both. What wisdom lies in opening ourselves to their mysteries. What gratitude I owe him for opening my mind and my heart, too.

Learning of his death, I felt as though I’d lost a friend. I’d written to him a few months back, after he published that column announcing his terminal cancer. My words felt grievously insufficient, but I thanked him for living his life and thus enriching mine. I included a copy of my latest book, but not because I wanted or expected him to read it; I only wanted to give him something, although that, too, felt grievously insufficient. He had given me so much.

This morning, I expressed these sentiments again. I hope he heard me, and I hope he hears me now, although I imagine the heavens are noisy with shouts of gratitude. Whether he hears me really doesn’t matter. I have to say it once more. Goodbye, Dr. Sacks. And thank you.