It's a shame that the martial arts craze that this show created (in conjunction with the ascendant popularity of Bruce Lee in the early 1970s), in conjunction with the somewhat cheesy '90s spinoff, has served to somewhat obscure what a gem it truly was.
It's heartbreaking to think that a lot of people who haven't seen the show lump it in as old, campy action television, like "The A-Team" or "Charlie's Angels" or something like that. The fact is, any given hour-long episode of "Kung Fu" probably contained about 45 to 60 seconds of actual action--if not less. The fact is, David Carradine was as good a leading man as any TV drama has ever had. And the fact is, far from being a cheap exploitation of martial arts and Eastern philosophy, "Kung Fu" was created and written in true reverance to those concepts. Meticulous research was conducted, and the lessons that Masters Kan and Po (wonderfully rendered by Philip Ahn and Keye Luke, respectively) teach Caine, and that Caine in turn teaches those he encounters, are routed in authentic Shaolin philosophy.
Nor was the show cheesily made. It involved lush cinematography by televisual standards and innovative use of devices such as forced perspective and slow motion (this was the first show or movie to use different gradations of speed within a single take--the shot would move at normal speed until Caine made contact with an elbow or a fist, and then suddenly switch to delicate, poetic slow motion).
Caine was a true archetype of television--a complete reversal of basically every American screen hero that went before. Not just peaceful--but passive and serene. As Caine described it--"Kung Fu" was an "anti-revenge television show"--an amazing concept when you think about it.
Remember, the American public was not even acquainted with the phrase "kung fu" before this show. Zen Buddhism was gaining popularity in the late '60s and early '70s, but no one had ever heard of Shaolin monks. The creators of this show took a big risk on an untested concept and came up with TV gold.