The word luminary comes from the Latin word luminaria, which means "light." A
luminary describes an important expert or leader in a particular field, such as
science, philosophy, literature, or business.
Why would a word whose root means "light" refer to a person who is a leader in
their chosen field or profession?
These experts or leaders often work in intense bursts after having sudden inspirations or "bright" ideas.
The experts and leaders are typically in charge of things and control who gets information, or "light," and who doesn't.
In a literal sense, light helps people see, and these people symbolically light the way for others in the field by their
achievements.