C.S. Lewis’s childhood nickname was Jacksie. When Lewis was four, an Irish terrier named Jacksie was killed by a car, and the young boy declared that he would henceforth be called Jacksie in the dog’s memory.
The name was gradually shortened and altered in everyday use. Lewis was later called Jack by his family and friends, and he eventually adopted C.S. Lewis as his published name. The “C.S.” stood for Clive Staples, his given names.
This story explains why biographies often say that Lewis disliked being called Clive. The nickname was not a literary pseudonym invented for his books; it began as a personal response to the death of a beloved family dog.
The detail also illustrates Lewis’s intense childhood imagination. He and Warren created imaginary worlds, and Lewis’s attachment to the name Jacksie became one of the small biographical episodes frequently cited in accounts of his early years.