Douglas C. Engelbart was 25, just engaged to be married and thinking about his future when he had an epiphany in 1950 that would change the world.

He had a good job working at a government aerospace laboratory in California, but he wanted to do something more with his life, something of value that might last, even outlive him. Then it came to him. In a single stroke he had what might be safely called a complete vision of the information age.

The epiphany spoke to him of technology’s potential to expand human intelligence, and from it he spun out a career that indeed had lasting impact. It led to a host of inventions that became the basis for the Internet and the modern personal computer.

In later years, one of those inventions was given a warmhearted name, evoking a small, furry creature given to scurrying across flat surfaces: the computer mouse.