＂Dear Mr. Sacks . . . You asked me if I could imagine what the world would look like when viewed with two eyes. I told you that I thought I could . . . But, I was wrong.＂

When Susan Barry first wrote to Oliver Sacks, she never expected a response, let alone the deep friendship that blossomed over ten years of letters. Now, she is sharing those letters for the first time.

In these letters, Susan lets us in on the boundless curiosity and insight that invigorated their one-of-a-kind friendship. It began when Sue--herself a neuroscientist--wrote to share an extraordinary development in her own medical history. Severely cross-eyed since birth, Sue had been told she would never acquire stereovision--the ability to see in 3D--and yet she did, a development at odds with decades of research. Within days, Oliver replied, ＂Your letter fills me with amazement and admiration.＂

Their shared interest in stereoscopy is just a taste of their regard for the power of science to provoke and enchant. Writing back and forth, they delve deeper into the mysteries of vision, are intrigued by the strange eye muscles of squid, and marvel at the adaptive capacity of the human body. Sue writes about the bioluminescent Noctiluca that congregate in the water around Cape Cod where she is spending the summer, and invites Oliver to visit. Together they delight in swimming in a bioluminescent sea.

In a painful twist of fate, as Sue’s vision improves, Oliver’s declines. And as it becomes harder for him to see, his characteristic small type shifts into large, capitalized font and he develops face blindness. Sue later recognizes this to be early signs of the cancer that ultimately ends his extraordinary life.

An often funny, richly informative, and amazingly intimate glimpse of a profound friendship, Dear Oliver inspires readers to appreciate treasured friendships and attests to the power of developing new ones, even late in life. This is, as Oliver writes, a joyful celebration of a ＂deep and stimulating friendship＂ that ＂has been a wonderful and unexpected addition to my life.＂