Who is C.S. Lewis from A Grief Observed and what is their importance?

Clive Staples Lewis, or Jack as he was called by friends, is both the narrator and the main character in this book as he sets out to turn his highly logical, well-read, and famously philosophical, introspective intellect to the subject of mourning the loss of his wife. He says he wanted to create a sort of map to describe the state as one watching it objectively and learning the pattern it followed.