Light produced by a flash unit is as natural as any other light source.
Hilarious wit.
I guess that's why flash units were invented in the 20th century, and need batteries or electricity to function. The Sun, this planet's greatest source of natural light, was invented in the 1920's, and is powered by just
four 1.5-volt AA batteries OR 110-volt AC wall current!
Flash units are also great for making garden plants grow; one simply fires one flash pop every 1.5 seconds, and after 10 years, the HEAT makes a nice warm climate over huge areas, and then the light rays from the Sun do the other 5%.