Whoa! This is really intersting! In 2010, Syd Hoare published online some translations of some of Jigoro Kano's writings. Included were the following passages involving Kano grousing about the deficiencies within the principle of Ju (as understood as winning by yielding)...
Most jujitsu was based on and carried out under the Ju principle in order to defeat the opponent. It was also applicable to all the day to day affairs of man. However Kano eventually came up against the fact that there were many occasions in both attack and defence which could only be dealt with by theories outside the yielding principle Kano giving examples of situations which could not be explained by the Ju/Yielding principle divided them into physical and mental ones.
For example when you are strongly grabbed from behind, under the JU principle there is no escape – there is no way to adapt to the opponent's power. There are a number of ways of responding to a strong hug from behind but there is no adaptation to the opponent's power. Similarly if an opponent grabs your throat from the front there are answers to it but they do not involve adapting to the opponent's power.
Furthermore if judo technique is always limited to complying with or adapting to the opponent's force there is nothing that judo can do if the opponent stands still. Even if you merely think about catching the opponents hand you cannot even lower your hand. All one can say is that it should be done with a minimum of force.Mental situations....When the opponent attacks you vigorously you have no time to think out new means to deal with it. You have no choice but to choose to reply to it with your old tricks which naturally float into your mind based on previous experience. If the opponent does not attack but only defends, your mental workings and new thoughts will not appear.
Furthermore when one has decided to try a technique on the opponent you must not hesitate or doubt whether you should do this or that but be resolute in your decision to try a technique. At the same time think about all possibilities and try moving around, doing techniques lightly and even though there may not be better methods one must not be idle in thinking about them and producing them. From all these illustrations, all methods of attack and defence are very difficult to explain with the simple JU principle. It is evident that whether considering the mental or physical aspects, that a new basic principle is necessary to cover the huge variety of judo technique.
rom about the period 1897 – 1907 Kano relied less and less on the JU principle to explain his judo. For example in 1900 he wrote in the Kokushi magazine, 'The number one requirement for nagewaza is the mobilization ofminimum force in order to throw the opponent how and where one wishes. In his explanations of the practical application of judo principles he wrote, 'People should put to work their God-given spiritual force to demonstrate as widely as possible meritorious deeds for the world and mankind.