I have studied de Jong's jujutsu grading system. Not just engaged in it but really studied it. I used 'the core of all learning' to study his grading system. The core of all learning, as I explain in my The Science Behind Fighting Techniques manuscript that I have just submitted to a publisher, is the identification of similarities and differences. It was by comparing what we do with what others do that I gained enormous insights. I learnt more about what we teach by studying what others teach than I could have simply by studying what we teach.
His grading system is a remarkable achievement. It is one of the most comprehensive grading systems in the world. It is all the more remarkable in that he developed it from what I believe to be scratch.
In Jan de Jong's Unique Grading System, I explain how he uniquely included gradings in his grading system that examine a candidates knowledge of why a technique works and their teaching abilities. His grading system uniquely develops black belts who are qualified teachers who know why a technique works in addition to knowing how to perform the technique (a la Gracie and Gracie, Brazilian Jiu-Jitsu: Theory and Technique).
The grading system is unique in using the shinken shobu no kata method to examine student's technical abilities. The term was taken from judo, however, the shinken shobu no kata used by de Jong is different to that taught by judo. Judo's shinken shobu no kata is a true kata in terms of choreographed attacks and defences. De Jong's is a kata in the sense that there are prescribed attacks and defences, however, those attacks are delivered in a random order thus simulating a fighting environment.
This method is used at the end of each class with various variations. Attacks are initiated based on the instructor's signalling which the defender cannot see. The defender can defend with any technique or they can defend using only the technique prescribed by the instructor which the attacks vary.
This method is in between true kata and free fighting. It instills a 'one punch, one kill' mindset; a committed defence that is designed to finish the fight there and then which free fighting often does not. The closest I've seen to it is Kyokushin karate's one-step sparring.
What is de Jong's legacy? Kaizen - continuous improvement. Those who are teaching can teach what de Jong taught, but, is that living up to de Jong's legacy? De Jong's grading system was a first effort, a remarkable achievement but still a first effort. There are errors in both technique and theory inherent in that grading system, which are the result of the lack of information that existed at the time he was developing it. In the spirit of kaizen we can address those errors. We can refine his grading system; grading system 2.0. I think this is what he would have wanted. For us to adopt the spirit of kaizen which was how he lived his budo life.
I think that to honour de Jong is to 'see further than he did.' As Newton said, 'If I can see further it is only by standing on the shoulders of giants.' He was a giant; we need to study and learn what he built, and then build upon that.
