This book contains the letters sent to D. Ezra S. Carr between the years 1866-1879. John Muir, naturalist and author, considered Mrs. Carr his 'spiritual mother' as she sympathised with his interest and aims. His letters are open and sensitive and therefore provide a particularly revealing insight into the young man's emotions and the life he led. Many of them are written from Yosemite Valley, America and so portray Muir's ardent scientific study of glacial geology and his joyous and reverent communion with nature. This book was originally published in 1915 and is here republished with an introductory biography of the author.