Jacksie was the name of C.S. Lewis’s childhood dog, remembered in Surprised by Joy.
Lewis described the death of the dog as a formative event in his early life. The animal had been named Jacksie after a family member’s wartime nickname, and Lewis later adopted the name for himself for a period. His brother Warren used “Jacksie” for him, and the nickname eventually developed into “Jack,” the name by which Lewis was commonly known.
Surprised by Joy, published in 1955, is Lewis’s spiritual autobiography. It traces experiences of longing, imagination, reading, friendship, and intellectual change rather than presenting a complete chronological account of every event in his life. The childhood dog episode is important because Lewis connects it with the origins of his chosen personal name.
The detail is easy to miss because Jacksie is not a character from Lewis’s fiction. It belongs to his autobiographical history, and the name should not be confused with the later nickname “Jack” used by friends and colleagues.