How does Sacks see the relationship between memory and life? How does Sacks see the connection in Jimmie G.?

Sacks believes that without memory one cannot have a real life and perhaps one cannot even have a soul. Sacks begins the chapter with a quote about how total memory loss means the loss of a life. When it comes to Jimmie G, Sacks' initial experiences cause him to worry about whether Jimmie has a soul at all. Jimmie's memory stopped in 1945 and he can no longer remember what he does. What sort of soul could such a person have? But later on, Sacks sees Jimmie in chapel and sees him calm and composed. He recognizes that there he has a soul.