Here is a nice, well-done video by PBS Arts showcasing the long and storied history of logo design. It features some of the top logo designers in recent history telling about the intricacies of logo design. Rarely do people look at the artistry that goes into making a logo. Its worth a look.
From PBS Arts
Off Book: The Art of Logo Design
Logos surround us in digital and physical space, but we rarely examine the thought and artistic thinking that goes into the design of these symbols. Utilizing a silent vocabulary of colors, shapes, and typography, logo designers give a visual identity to companies and organizations of all types. From cave painters to modern designers, artists throughout history have been reducing the complex down to simple ideas that communicate with the world.