First and foremost, jeet kune do translates as "the Way of the intercepting fist." It does not mean "the way of the eclectic fist"! As a non-classical fighting art, jeet kune do is based on skill, not on how many techniques, arts or forms you know. As my good friend and fellow jeet kune do teacher Steve Golden says, "Jeet kune do is simple (not a lot of moves), but not easy!"
In fact, it takes a tremendous level of skill to shut down an opponent with as few moves as possible. This means that to attain this skill level, each and every attack you launch must be devastating to your adversary. Jeet kune do is not for the dabbler or the faint of heart. Is your lead punch a "probe" or does it posses the necessary stopping power to shut down your opponent on the first move?
Simple-as in as few moves as possible? Yes. Easy-as in requiring supreme timing, distance, and power? Not a chance.
So, using the underlying principle of simplicity, we can now define the art. The definition of jeet kune do is: To intercept your opponent's intentions as quickly and efficiently as possible with the least amount of moves. This is why the principles of economy and simplicity are so essential to understanding JKD. As of this writing, "so-called" JKD practitioners are using four, five and even more moves to stop a simple jab! If you aren't hitting until the sixth movement, how can this be called jeet kune do? Why use 10 or even five movements when one will get the job done?
Allow me to use an analogy to illustrate my point: If I want to leave my house, would I crawl out a window, shimmy down the drainpipe, jump down two stories and hope to land in a tree? Or, would I simply walk out the front door? Wouldn't that be a more efficient way to leave? Isn't the simplest, non-complicated and most direct way the best?
According to the underlying principles of jeet kune do, the answer is always a resounding "yes." So by now, I hope you are seeing that jeet kune do is not merely "what works for you." That is probably something all together different from the true expression of JKD. The principles of interception and simplicity require a minimum of wasted movements on the part of the jeet kune do practitioner. It is truly the most sophisticated method of fighting, because it does not allow for even one response from your opponent. And for this to occur, the JKD man or woman has to be in complete control of his tools. Using this method, the opponent's intention to attack leads inevitably to his own defeat.
By delving into the guiding principles of jeet kune do, this book will offer insights into the true nature of the art. We will be discussing and demonstrating right and wrong whenever the principles are violated. These guiding principles include: Simplicity (Uncomplicated); Economy of Motion; Longest Weapon to the Nearest Target; No Passive Moves; and Attack the Attack. Once you appreciate the meaning of these principles, you can judge for yourself if you are expressing the JKD Way of Combat. While the task may seem daunting, I will repeat what my instructor, Bruce Lee, said to me when I balked at doing splits between two chairs: "Something to shoot for, Jerry!"
The NPM Principle-No Passive Moves
One of the most important, but least understood, aspects of jeet kune do is the No Passive Moves (NPM) Principle. Some years ago, I coined this term to explain the difference between jeet kune do and more classical martial arts. This is really the final stage of hitting on every move. (Bruce decided to call all attacks a "hit," whether with the hands, legs, etc.). This underlying principle is used in every range of combat.
The most basic response to every threat is a straight blast or a barrage of nonstop linear punches that intercepts the opponent's first move. It smothers the opponent and neutralizes any hope of follow-ups.
NPM Bob and Weave
The bob and weave or duck is one of the most common defenses taught against a hook. Here's how Bruce Lee modified it to fit his NPM principle: Instead of bobbing and coming up and then punching with a hook, the jeet kune do artist strives to hit on the first move, and each one thereafter. If you are caught and have to resort to a duck, etc., you would never use two passive (non-hitting) movements in a row.
Simplicity First
What could be simpler than no passive moves? It is much more complicated to defend first and then counter. But does simple (uncomplicated) mean it's easy? Just the opposite. When you see a punch flying at your head, it's much more instinctive to cover up, duck, block and turn away. So hitting on every move has to be trained until it is another JKD second-nature reflex. A reflex well worth acquiring, it is the essential principle in jeet kune do combat.
NPM of JKD INCORRECT
 Jerry prepares to attack (1). |  When he fires a punch, Dimitri parries (2) |  and parries again (3). |
 He then does a pak sao (4) |  and finally hits (5). |
CORRECT NPM
 On the opponent's first motion (1), |  Jerry explodes with a simultaneous pak sao and hit (2). |
Source : insidekung-fu.com
