- In Randori we teach the pupil to act on the fundamental principles of Judo, no matter how physically inferior his opponent may seem to him, and even if by sheer strength he can easily overcome him; because if he acts contrary to principle his opponent will never be convinced of defeat, no matter what brute strength he may have used.
- Judo is the way to the most effective use of both physical and spiritual strength. By training you in attacks and defenses it refines your body and your soul and helps you make the spiritual essence of Judo a part of your very being. In this way you are able to perfect yourself and contribute something of value to the world. This is the final goal of Judo discipline.
- As quoted in Dynamic Judo (1967) by Kazuzo Kudo; also in Chasing Dragons : An Introduction to the Martial Arts Film (2006) by David West, p. 10
- Generally speaking, if we look at sports we find that their strong point is that because they are competitive they are interesting, and young people are likely to be attracted to them. No matter how valuable the method of physical education, if it is not put into practice, it will serve no purpose — therein lies the advantage of sports. But, in this regard there are matters to which we must also give a great deal of consideration. First, so-called sports were not created for the purpose of physical education; one competes for another purpose, namely, to win. Accordingly, the muscles are not necessarily developed in a balanced way, and in some cases the body is pushed too far or even injured. For that reason, while there is no doubt that sports are a good thing, serious consideration must be given to the selection of the sport and the training method. Sports must not be undertaken carelessly, over-zealously, or without restraint. However, it is safe to say that competitive sports are a form of physical education that should be promoted with this advice in mind. The reason I have worked to popularize sports for more than twenty years and that I have strived to bring the Olympic Games to Japan is entirely because I recognize these merits. However, in times like these, when many people are enthusiastic about sports, I would like to remind them of the adverse effects of sports as well. I also urge them to keep in mind the goals of physical education—to develop a sound body that is useful to you in your daily life — and be sure to consider whether or not the method of training is in keeping with the concept of seiryoku zenyo.
- "Judo and Physical Training" in Mind Over Muscle : Writings from the Founder of Judo (2006) edited by Naoki Murata, p. 57
- If there is effort, there is always accomplishment.
- As quoted in Black Belt : Judo Skills and Techniques (2006) by Neil Ohlenkamp, p. 36
Kodokan Judo (1882) 
- Kodokan Judo : The Essential Guide to Judo by Its Fouder Jigoro Kano (1986 translation, page numbers from 1994 edition); some quotes also in "Principles and Aims of Kodokan Judo" at yoshinjujitsu.com
- In randori, one must search out the opponent's weaknesses and be ready to attack with all the resources at his disposal the moment the opportunity presents itself, without violating the rules of judo.
- p. 22
- In randori we learn to employ the principle of maximum efficiency even when we could easily overpower an opponent. Indeed, it is much more impressive to beat an opponent with proper technique than with brute force. This lesson is equally applicable in daily life: the student realized persuasion backed up by sound logic is ultimately more effective than coercion.
- p. 23
- Another tenet of randori is to apply just the right amount of force — never too much, never too little. All of us know of people who have failed to accomplish what they set out to do because of not properly gauging the amount of effort required. At one extreme, they fall short of the mark; at the other, they do not know when to stop.
- p. 23
- There are people who are excitable by nature and allow themselves to become angry for the most trivial of reasons. Judo can help such people learn to control themselves. Through training, they quickly realize that anger is a waste of energy, that it has only negative effects on the self and others.
- p. 23
- Judo teaches us to look for the best possible course of action, whatever the individual circumstances, and helps us to understand that worry is a waste of energy. Paradoxically, the man who has failed and one who is at the peak of success are in exactly the same position. Each must decide what he will do next, choose the course that will lead him to the future. The teachings of judo give each the same potential for success, in the former instance guiding a man out of lethargy and disappointment to a state of vigorous activity.
- p. 23
- One more type who can benefit from the practice of judo are the chronically discontented, who readily blame others for what is really their own fault. These people come to realize that their negative frame of mind runs counter to the principle of maximum efficiency and that living in conformity with the principle is the key to a forward-looking mental state.
- p. 24
- Walk a single path, becoming neither cocky with victory nor broken with defeat, without forgetting caution when all is quiet or becoming frightened when danger threatens.
- p. 25
- Before and after practicing Judo or engaging in a match, opponents bow to each other. Bowing is an expression of gratitude and respect. In effect, you are thanking your opponent for giving you the opportunity to improve your technique.
- P. 31
Budokwai Bulletin (1947) 
- Jigaro Kano, as quoted by Gunji Koizumi in the Budokwai Bulletin (April 1947)
- I have been asked by people of various sections as to the wisdom and possibility of Judo being introduced with other games and sports at the Olympic Games. My view on the matter, at present, is rather passive. If it be the desire of other member countries, I have no objection. But I do not feel inclined to take any initiative. For one thing, Judo in reality is not a mere sport or game. I regard it as a principle of life, art and science. In fact, it is a means for personal cultural attainment. Only one of the forms of Judo training, so-called randori or free practice can be classed as a form of sport. Certainly, to some extent, the same may be said of boxing and fencing, but today they are practiced and conducted as sports. Then the Olympic Games are so strongly flavored with nationalism that it is possible to be influenced by it and to develop "Contest Judo", a retrograde form as ju-jitsu was before the Kodokan was founded.
- Judo should be free as art and science from any external influences, political, national, racial, and financial or any other organized interest. And all things connected with it should be directed to its ultimate object, the "Benefit of Humanity". Human sacrifice is a matter of ancient history.
- Another point is the meaning of professionalism. With Judo, we have no professionals in the same sense as other sports. No one is allowed to take part in public entertainment for personal gain. Teachers certainly receive remuneration for their services, but that is in no way degrading. The professional is held in high regard like the officers of a religious organization or a professor in the educational world. Judo itself is held by us all in a position at the high altar. To reconcile this point of view with the Western idea is difficult. Success or a satisfactory result of joining the Olympic Games would much depend on the degree of understanding of Judo by the other participating countries.
Kodokan Magazine (1974) 
- Statements of Jigoro Kano (circa 1934), quoted in "Mission of Kodokan Judo", by D. Risei Kano, in Kodokan Magazine (February 1974)
- Recently in our country, there has been a steadily increasing number of people who dislike work and pursue leisure and extravagance. Almost everywhere individuals and organizations are fighting with resultant loss of energy that is needed for positive action. In order to save them from this situation, a principle of judo, based on the maximum efficiency concept should be applied as one aspect of modern society and as a natural result of the application of the principle of maximum efficiency, a mutual welfare and prosperity is believed to be the only effective way to ease and neutralize the forces among these individuals and organizations.
- Also quoted in "Hints For Judo" by D. Risei Kano, at usadojo.com
- In our society today, when we teach the righteous way of life based upon the Theory of judo which embodies the principles of continuous improvement of society, then this righteous life provides a basis of definite proof of this principle and unifies the peoples' way of thinking. Various religious and learned points of view are then made abundantly clear.
Budo Secrets (2002) 
- Budo Secrets: Teachings of the Martial Arts Masters (2002) by John Stevens
- Jigoro Kano's Five Principles of Judo:
1. Carefully observe oneself and one's situation, carefully observe others, and carefully observe one's environment,
2. Seize the initiative in whatever you undertake,
3. Consider fully, act decisively,
4. Know when to stop,
5. Keep to the middle.