The book "Life and Letters of Father George Mortimer, M.A. Pope of Thornhill Cathedral in the Diocese of Toronto, Canada West" by John Armstrong is a valuable document that tells about the life and ministry of an outstanding spiritual figure of the 19th century. This book reflects the most important moments of the biography and activities of Fr. Mortimer, his struggle for truth and justice, his spiritual discoveries and views on church service. The author presents to the reader the unique letters and memories of Father Mortimer, which help to better understand his personality and mission. Thanks to the detailed analysis and interpretation of life facts, the book reveals to the reader a picture of the era in which this outstanding priest had to live and act. "The Life and Letters of the Rev. George Mortimer, M.A. Rector of Thornhill, in the Diocese of Toronto, Canada West" is an important literary work that not only reproduces the story of one individual, but also opens the broad context of the history of Canada in the 19th century and church reforms of that period.